Leaders from the two main rebel groups in Sudan's western Darfur (search) region have agreed to participate in "substantive negotiations" for a political solution to the humanitarian crisis, a U.N. spokesman said.

The announcement came a day after a round of peace talks in Geneva mediated by the African Union.

"The leadership of two rebel groups in Sudan's Darfur region today agreed to take part in substantive negotiations to resolve the political dispute," U.N. spokesman Fred Eckhard said Friday.

He added that the next step was for African Union (search) and U.N. officials to discuss with the Sudanese government when talks between it and the rebel groups could resume.

A first round of peace talks at the African Union headquarters in Ethiopia were suspended last Saturday after just two days when rebels walked out.

The Sudan People's Liberation Movement (search) and the Justice and Equality Movement (search) had insisted that the Sudanese government honor the terms of previous peace agreements before beginning a fresh round of talks.

A 15-month conflict in western Sudan's vast Darfur region has killed as many as 30,000 people and forced over a million to flee their homes. The violence has also left more than 2 million people in desperate need of food and medicine.

The violence began when two groups from Darfur's African tribes took up arms over what they regard as unjust treatment by the government in their struggle over land and resources with Arab countrymen.

The fighting has worsened as Arab militiamen have waged a campaign to force black Africans from their homes.

The Janjaweed -- the main Arab militia blamed for much of the violence -- was not participating in the talks.

Eckhard also said that Secretary-General Kofi Annan was sending his special representative on internally displaced people to the region. The envoy, Francis Deng, was to begin a weeklong visit to Sudan on Saturday.