MANILA, Philippines ? The Philippine government and Muslim guerrillas can no longer strike a final peace accord before President Gloria Macapagal-Arroyo steps down in June because of limited time and differences in ongoing peace talks, the country's chief negotiator said Tuesday.

The government has focused its effort to forging an interim accord that will primarily commit the 11,000-strong Moro Islamic Liberation Front to continue negotiations with the next president to peacefully settle its decades-old insurrection, chief government negotiator Rafael Seguis said.

"We admit we will no longer be able to sign a comprehensive compact at this time considering the time constraints," Seguis told a news conference.

Muslim rebel spokesman Eid Kabalu agreed, saying the chances of forging a peace pact was "zero," considering the disparity between the government and rebel positions on many issues.

Several demands submitted by the rebels during negotiations brokered by Malaysia in January would require the passage by congress of new laws, including a proposal to drastically strengthen the powers of minority Muslims to run an existing Muslim autonomous region in the country's south, Seguis said.

The rebel front is the largest of at least four guerrilla groups waging a bloody rebellion in southern Mindanao region for decades. More than 120,000 people have died in repeated clashes with government troops, and the conflict has held back economic progress in some of the country's poorest regions.

Government officials and the rebels resumed talks in December after years of peace negotiations broke down in 2008 when the Philippine Supreme Court declared a preliminary pact unconstitutional.

This led to clashes that killed hundreds and displaced about 750,000 people. Fighting has subsided since last July, but about 100,000 people remain displaced, according to the International Committee of the Red Cross.

The United States and Australia have backed the talks, fearing rebel strongholds could harbor al-Qaeda linked militants.