US Secretary of State Hillary Clinton on Wednesday called Sudanese leaders in a bid to defuse what she called the "ticking time bomb" of an inevitable secession of the country?s restive and oil-rich south.

US President Barack Obama meanwhile prepared to attend a meeting on Sudan at UN headquarters on September 24 to show the importance Washington places on a January 9 referendum on whether the south should stay united with the north.

Aides said Clinton made the calls to Sudan's vice president Ali Osman Taha and Salva Kiir, who heads the autonomous south under the 2005 Comprehensive Peace Agreement (CPA) that ended a 22-year civil war between north and south.

She urged the representatives of the Arab-dominated central government and the south to fully implement the peace deal and prepare for the referendum provided for under the CPA, her spokesman Philip Crowley told reporters.

As a follow-up, the US special envoy for Sudan, Scott Gration, will on Thursday travel back to Sudan to continue the high-level talks, Crowley said.

Speaking to foreign policy experts, Clinton said the United States is also involving the African Union and South Africa as well as European countries Britain and Norway in the diplomatic push to ensure a smooth referendum.

"It's really all hands on deck," the chief US diplomat said during a question-and-answer session following a speech she gave at the Council on Foreign Relations.

"The situation north/south is a ticking time-bomb of enormous consequence," Clinton said.

"The time frame is very short. Pulling together this referendum is going to be difficult," she said.

"But the real problem is, what happens when the inevitable happens and the referendum is passed and the south declares independence?" added Clinton, the highest-ranking US official so far to say secession is a foregone conclusion.

"So simultaneously, we're trying to begin negotiations to work out some of those intractable problems. What happens to the oil revenues?," she asked.

"I mean, if you're in the north, and all of a sudden you think a line's going to be drawn and you're going to lose 80 percent of the oil revenues, you're not a very enthusiastic participant," she warned.

Clinton said the United States is working with both regional and international partners to "figure out some ways to make it worth their while (in the north) to peacefully accept an independent South."

The south will also have to make "some accommodations" with the north "unless they want more years of warfare," she warned.

Semi-autonomous south Sudan is struggling to recover from the war, Africa's longest civil conflict which left an estimated two million people dead and was fueled by ethnicity, ideology, religion and resources such as oil.

The border was meant to be defined six months after the CPA was signed, but negotiations by the committee established to demarcate it are in "deadlock," the International Crisis Group think tank said.

The Brussels-based ICG said last week that some border areas "remain dangerously militarized" as the oil issue raises the stakes for drawing boundaries.

In New York, Susan Rice, US ambassador to the United Nations, said the September 24 meeting Obama, other heads of state and foreign ministers will attend will send "an important signal to the people of Sudan, in the north and south, and Darfur and beyond" about the international commitment to the CPA.

The United Nations says 300,000 people have died in the western Darfur region since minority rebels revolted against the central government in 2003, and 2.7 million people have fled their homes from the fighting.

The government in Khartoum says 10,000 people have been killed.

Nigeria will hold its presidential election in January, giving the oil-rich nation only four months to register voters and untangle its notoriously corrupt electoral system.

The Independent National Electoral Commission announced Tuesday that the presidential election would be held Jan. 22, sandwiched between a Jan. 15 election for the National Assembly and a Jan. 29 election for state offices. In the interim, the commission plans create a new registry for an estimated 70 million eligible voters in Africa's most populous nation.

However, the commission has yet to even order the computers it plans to use in November to register voters across Nigeria's sprawling cities and rural villages. Nor has it begun to hire the estimated 50,000 poll workers it will need to run the election, leading some to wonder whether the coming polls will mirror the nation's ballot-box stuffing past.

"I think we can achieve a modicum — and I underline that word — a modicum of credibility," said Innocent Chukwuma, a Nigerian poll monitor now teaching at Harvard University's John F. Kennedy School of Government. "The time is too short to expect them to perform magic."

After gaining independence from Britain in 1960, Nigeria, an oil-rich country with a population of 150 million, suffered through a string of military dictatorships and coups.

The country became a democracy through a presidential election in 1999, but its polls remained mired in vote-rigging, violence and political thuggery. The People's Democratic Party, composed of the nation's elite, carries the political muscle necessary to ensure its candidate makes it into the presidential villa of Aso Rock. International observers called the 2007 election of President Umaru Yar'Adua rigged, even though it represented the first civilian-to-civilian transfer of power in the nation's history.

Yar'Adua entered office vowing to reform the system that put him in power, but died in May without any of his promised reforms became law. Vice President Goodluck Jonathan, who took office after Yar'Adua's death, has said his highest goal is to ensure "that all votes count and are counted" in the 2011 election.

However, Jonathan has declined to say whether he'll seek the presidency, casting a sense of unease across the election. Former military dictator Ibrahim Babangida and former vice president Atiku Abubakar both have said they want to contest the election as the ruling party's candidate.

"We cannot have a situation like we had during the former dispensation where election results were written in hotel rooms and given to the (election) chairman to sign," said Emma Ezeazu, general secretary of the Alliance for a Credible Election.

Many applauded Jonathan for appointing Attahiru Jega, an academic with popular appeal, as the new leader of the national electoral commission. However, the commission has yet to purchase the equipment needed to make an entirely new voter registry, as many considered the 2007 list riddled with errors and fraud.

Election monitors say the government must allow members of the public to double-check their names and information against the list to ensure its accuracy. The electoral commission has set aside five days in late November for that, so long as the registration occurs on time.

The commission also must ensure that its poll workers refuse politicians' bribes and strong-arm tactics, Chukwuma said. Otherwise, he warned the new registry would become an accurate, yet ignored list.

When the registration starts "and things are not done the way they said they would do it, that's when the doubts will start," the professor said. "In this period, all we can do is hope for the best and perhaps prepare for the worst.

South Africa – South African civil servants unions are suspending a nationwide strike for higher wages to give members time to consider the government's latest offer, labor leaders said Monday.

At a news conference on the 20th day of a strike that has crippled hospitals and schools in Africa's most vibrant economy, Chris Klopper, who leads a coalition of government worker unions, said the suspension was immediate.

"We want workers to return to work as soon as possible, and that means tomorrow," Klopper said.

Earlier, Thobile Ntola, president of the South African Democratic Teachers Union, broke the news to red-shirted members of his union gathered at the gates of the complex where leaders had come to the suspension decision. The members shouted in protest when Ntola told them numbers at the picket lines were dropping.

"There comes a time in any strike in which we must weigh our options," Ntola said.

The government responded to the move by saying in a statement it was "optimistic that a final position of the unions will soon remove the cloud of doubt and uncertainty that continues to engulf the nation."

In a joint statement, some two dozen unions said the strike produced a victory for labor, saying the government had moved from offering a 5.2 percent wage increase to 7.5. Unions want 8.6.

When the government made its 7.5 percent offer last week, union leaders said their members had rejected it. Then they said they needed more time to more fully explain the offer to workers.

The South African public has shown increasing impatience with the strike, which has sometimes been violent.

Nurses who have crossed picket lines at hospitals have been beaten by striking colleagues. Volunteers and army medics have been called in to help at hospitals, and some of the most fragile patients have been moved to private hospitals.

Students in their final year are worried they will not be able to graduate on time. Judges have told jailed suspects their pleas for bail cannot be heard for want of interpreters and other court staff.

Ntola told reporters it was the government, not the workers, who had caused the strike. He said President Jacob Zuma went on an international trip instead of showing leadership when talks stalled.

"What has the president done? He has left the country and gone to China," Ntola said.

On returning at the end of August from a trip at which he sealed business deals, Zuma called on negotiators to resume talks. The new government offer came soon after.

Ntola rejected criticism that the strike could hurt South Africa's reputation among potential foreign investors. He said economic growth must be built on good wages for those providing government services.

He also said Cabinet ministers and top officials should forgo their own raises.

"Our demands are genuine," he said. "The inequalities in this country are very vast, and they need to be closed."

President Ellen Johnson Sirleaf on Monday hailed the launch of a Delta Airlines flight linking Liberia to the United States as a boost for business and tourism in the west African nation.

On Sunday, Delta Airlines became the first American carrier to fly to Liberia in twenty years.

"Delta Airline's inaugural direct flight from Monrovia to the United States opens the sky over Liberia for business, for commerce, for tourism, for travel," Sirleaf said in a statement from the presidency issued Monday.

The service will operate weekly between Monrovia and Delta?s hub at Hartsfield-Jackson Atlanta International Airport, with a stop in Accra, Ghana.

Liberia, founded by freed American slaves in 1822, is Africa's oldest independent state and Sirleaf said maintaining a link with the United States was an "economic necessity".

Pan-American airlines used to fly between the United States and Monrovia until they pulled out in 1990, a year after the outbreak of a civil war which would last until 2003, leaving the country in ruins.