Lagos, Nigeria ? Two of the three rebel groups battling in Sudan’s troubled Darfur region refused early today to sign a peace plan, possibly jeopardizing the accord aimed at resolving a crisis that has cost at least 180,000 lives.

Abdelwahid Muhamed El Nur of the main rebel Sudan Liberation Army walked out of the meeting with negotiators, saying, “We are not going to sign.”

The action came shortly after the leader of a smaller group issued a similar declaration, while a splinter rebel faction said it needed time to consult with colleagues in Sudan and would return later in the morning.

The decisions culminated days of intense talks that involved Sudan’s government, the African Union, rebels and envoys from the United States, the European Union and Britain.

Decades of low-level tribal clashes over land and water in Darfur erupted into large-scale violence in early 2003 with rebels demanding regional autonomy. The central government is accused of responding by unleashing Janjaweed militias upon civilians, a charge Sudan denies.

At least 180,000 people have been killed and more than 2 million forced to flee their homes.