Khartoum has refused to confirm the SPLA assertion. But Sudanese leaders have been warning of the prospect of another civil war should the south vote for independence.

"Despite our commitment to the Comprehensive Peace Agreement, we will not accept an alternative to unity," Sudanese President Omar Bashir said on Oct. 19. "Unity is the probable outcome for the south if it is given freedom of choice in a fair, free election. Sound logic leads the south to unity."

SPLA officials said Khartoum has deployed at least 30,000 troops in Kordofan as well as energy fields in Heglig and Unity. They said the troops were conducting training and maneuvers that reflected preparations for a massive offensive.

"We've raised the issue with the UN several times, but they haven't responded," an official said.

Matt Paul, the SPLA's representative to the UN ceasefire commission, said the buildup of the Khartoum military began in June 2010. He said large numbers of northern Sudanese troops have arrived in Kordofan.

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