Al-Bashir's announcement is part of a high-profile campaign by Khartoum to display its readiness amid attempts to cobble together new Darfur peace negotiations mediated by the Arab nation Qatar and a U.N. envoy. It comes as the Sudanese president is trying to fend off possible genocide charges by the International Criminal Court over atrocities in Darfur.
Up to 300,000 people have been killed and 2.5 million driven from their homes in the vast region of western Sudan since fighting erupted in early 2003. The war pits troops from the Arab-led Sudanese government against ethnic African rebels, and Khartoum is accused of backing Arab militias known as janjaweed said to have carried out widespread atrocities against ethnic African civilians.
The government has repeatedly called ceasefires in Darfur in the past, but they have quickly broken down.
Al-Bashir urged rebels to join Khartoum in peace talks, speaking at a conference of Sudanese political parties, southern Sudanese and some Darfur tribal leaders that he convened to recommend ways to move ahead with peace.
"I am sending a special message to my brothers in the armed movements to come together (with us) for a joint single word, through which we would be able to realize peace ... security and stability for our people," he told the gathering, known as the Darfur National Forum.
He announced his "agreement to an immediate, unconditional ceasefire between the armed forces and the warring factions, provided that an effective monitoring mechanism be put into action and be observed by all involved parties."
The call appeared to stop short of ordering a unilateral ceasefire by government troops in Darfur.
Al-Bashir promised an "immediate campaign to disarm the militias and restrict the use of weapons among armed groups." The disarming of the janjaweed has been a top demand of Darfur rebels.
In another gesture, al-Bashir also said his government is willing to pay compensation to Darfurians who lost their homes to help them return and rebuild. He promised to "empower" the U.N.-African Union peacekeeping force that is deployed in Darfur "to carry out its role effectively."
A top official in the peacekeeping force, known as UNAMID, welcomed the agreement and said the U.N. and Qatar would now approach rebel leaders to try to bring them into a cease-fire.
"The government has put something concrete on the table for discussion. It puts on the table ... almost all the issues the rebels have demanded," Ali Hassan, the head of UNAMID in southern Darfur, told The Associated Press.
But Darfur rebel leaders rejected any immediate ceasefire.
Abdulwahid Elnur, the exiled leader of the Sudan Liberation Movement, said the rebels cannot accept any ceasefire until the janjaweed are disarmed.
"We need action not words from them," he told AP. "It's not a matter of the ceasefire, it's a matter of stopping the genocide ... We don't trust these people."
Suleiman Sandal, a top commander from another main rebel force, the Justice and Equality Movement, said "this government is not serious about peace ... and is preparing for war on all fronts." He rejected any ceasefire unless it was part of a "framework agreement."
AP correspondent Sarah El Deeb in Nyala, Sudan, contributed to this report.