Washington: 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 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? 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 per cent of the oil revenues, you're not a very enthusiastic participant," she added.