The main militant group in Nigeria's oil-rich southern region said Tuesday that it is willing to cease hostilities if the federal government agrees to mediation by Jimmy Carter.

The Movement for the Emancipation of the Niger Delta said the former U.S. president had accepted their invitation to help negotiate an end to the long-running conflict that has disrupted petroleum exports and contributed to the sharp rise in oil prices.

Militants say they received Carter's acceptance from John Stremlau, an official of Carter's organization. But Stremlau told The Associated Press only that Carter was generally ready to be "helpful in the quest for peace."

"It would have to be all sides of the conflict," Stremlau said. "There's no point in becoming a pawn of one partisan group or another."

Government officials were not immediately available for comment. The Nigerian government considers the conflict is an internal matter.

The militants issued a statement saying they would call off all hostilities and observe a temporary cease-fire if the Nigerian government accepted the Carter initiative.

"However, if as expected, the government fails to seize on this new opportunity for peace, our actions will continue to speak volumes beyond the Nigerian shores," the statement said.

The militants have stepped up activities in the weeks since one of their presumed leaders, Henry Okah, went on trial charged with treason and terrorism. He could face the death penalty if convicted.

A string of pipeline bombings in recent weeks has cut oil production in Africa's biggest petroleum exporter by tens of thousands of barrels a day.

The militants, who say they are seeking to force the federal government to share more oil revenues with their impoverished region, have also stepped up propaganda efforts in an apparent attempt to increase visibility.