Martin Luther Agwai, the commander of African Union peacekeepers in Darfur, said civilians converged on their base nearby for safety.
His troops treated about two dozen injured civilians and combatants, but did not allow them to enter the base.
Minni Minnawi was the only one of three rebel negotiating groups to sign a May 2006 peace deal with Khartoum.
'Stab in the back'
After the signing of the May 2006 peace deal with Khartoum, the movement became part of the government.
"Genocide is a crime against humanity as a whole, not just against it's immediate targets. It therefore falls on the world at large to act."
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Dirbeen said on Monday the raid was a "stab in the back of the Darfur peace agreement".
A UN official said Monday's attack and charges by rebels that troops had razed another Darfur town and killed 100 people in retaliation for an attack on African Union troops last month, showed the need to provide a planned UN-AU peacekeeping force with sufficient mobility and firepower.
Jean-Marie Guehenno, head of UN peacekeeping operations, said he was "very concerned" with the escalating violence in Darfur less than three weeks before scheduled peace talks in Libya.
The talks in Tripoli on October 27 are to encourage other factions to sign up to peace.
"At this stage, we cannot formally confirm any particular responsibility but it's very troubling that the city which was under the control of the government of Sudan could be burnt down," Guehenno said.
The French diplomat added that the incident "shows the importance of having troops that are very mobile, with the capacity to dominate any situation".
Darfur, in western Sudan, has suffered widespread fighting since 2003, killing about 200,000 people and forcing 2.5 million from their homes.