Sudanese officials asked international peacekeepers to leave a town in Darfur, the UN and Sudanese officials said on Sunday. The challenge to the fragile international mission could pose a serious challenge to peace in the troubled region, observers said. Sudan wants to launch an offensive against rebels from the Justice and Equality Movement, a rebel group known to have occasionally received Chadian support that has held the south Darfur town of Muhajeria since mid-January, said Akuei Bona Malwal, Sudan's ambassador to the African Union. "We are not ordering them around, we are asking them," Malwal said. "It's sort of like informing them, 'something will be happening here."' Sunday's request is the first of its kind that the Sudanese government has made, UN officials said.