KHARTOUM, Sudan — Darfur’s most-wanted rebel leader vowed yesterday to keep up his offensive against the Sudanese government, saying he can exhaust the military by fighting it all across Africa’s largest nation.

In a phone interview with the Associated Press, Khalil Ibrahim said the military success of the Justice and Equality Movement is easy to explain. “We are more spread out and we move fast.”

The speed of his forces was widely credited with allowing Mr. Ibrahim’s men to reach the outskirts of Khartoum to launch an attack Saturday. They set out from the Darfur and Kordofan regions under cover of night in trucks. They were spotted by the military but outran pursuers as they raced across the terrain of central Sudan.

“The government can’t keep up with the JEM,” Mr. Ibrahim said. “It will be exhausted … We can move from the north, south, west and east freely.”

Mr. Ibrahim said he was speaking by phone while on the run in the capital’s twin city of Omdurman, where his rebels staged the daring raid. It is the closest that Darfur’s rebels have ever gotten to the seat of the government.