Four African heads of state and other officials are meeting in Chad to discuss the security situation in the war-torn Darfur region of western Sudan.  At least one rebel group is set to meet with Sudanese government officials on the sidelines.

Chadian President Idriss Deby is hosting the two-day summit, at which the leaders of Sudan, Congo-Brazzaville, and Gabon, an official representing the Nigerian president, the chairman of the commission of the African Union, and representatives from Libya and Egypt are looking at ways to enforce a ceasefire in Darfur.

For two years, government forces, a militia known as the janjaweed that is believed to be backed by the government, and two rebel groups have been battling one another and local residents of Darfur.

Last year, the Sudanese government and the rebels groups signed a ceasefire to end their fighting, an agreement that has since been violated many times.

On the sidelines of the summit is another meeting, scheduled for late Wednesday, between the Sudanese government and the rebel group Sudan Liberation Movement.

The rebel group's general coordinator, Adam Ali Shogar, says the ceasefire, monitored by a commission of government and rebel representatives, will be the main topic of conversation.

"The chairman of [the] ceasefire commission will address the meeting,? he said.  ?And we'll see if there is any improvement on the ground there.  Also, [from] what I understood from the agenda, there is a plan for strengthening the joint commission itself and the ceasefire commission in El-Fashir in Darfur."

The conflict has killed more than 50,000 people and displaced more than one million.

The United Nations last month said gross human rights violations have taken place in Darfur.  The conflict has been called one of the world's worst humanitarian disasters.