KUALA LUMPUR - The government and the country's largest Muslim rebel group moved on Saturday to implement their peace agreement "as soon as possible" and establish a new autonomous government in the south before lawmakers rewrite the Constitution.

The proposed Bangsamoro government will be a "test bed" for President Rodrigo Duterte's plan to devolve power to the regions under a new federal government that he wants to put in place within his term, Presidential Peace Adviser Jesus Dureza said.

The meeting here quelled fears that the two-year-old peace accord, which was forged under Duterte's predecessor, Benigno Aquino, would take a backseat to efforts to change the country's form of government.

"We'd like to see it also as test bed, a model for what could be a federal state later on when we establish the federal set-up in the Philippines," Dureza told reporters here. "That's the end game."

Moro Islamic Liberation Front Chairman chairman Murad Ebrahim stressed the urgency of implementing the peace deal, aimed at ending four decades of fighting in the south that has claimed 100,000 lives.

"There must be a final closure to this cycle of conflict in Mindanao. The time to do so is now, not later."

Both sides sat down Saturday to discuss how to implement the 2014 Comprehensive Agreement on the Bangsamoro, which was thrown into uncertainty after the last Congress failed to pass a law that would implement it.

Some lawmakers said the proposed Bangsamoro Basic Law (BBL) had some unconstitutional provisions. Debates were also derailed by public outrage over the deaths of 44 police commandos in a botched anti-terror raid.

Dureza was accompanied by Speaker Pantaleon Alvarez and Majority Leader Rudy Fariñas, who will call the shots on the new Bangsamoro law at the House of Representatives.

Murad said the BBL would still be the "working paper" of the new draft to be prepared by the 15-member Bangsamoro Transition Commission.

"We are willing to enhance provisions of the BBL to accommodate other concerns from different groups," he said after both sides launched the implementation phase of the peace process here.

"We hope that with the 17th Congress, it will be a brighter future for the enabling law."

Dureza said Congress could pass a version of the law without the supposedly unconstitutional provisions of the old BBL. He said these provisions could then be addressed when Congress, sitting as a constituent assembly, revises the 1987 Constitution toward a federal system of government.

Murad said both sides should first agree on which provisions of the BBL were unconstitutional.

Critics of the BBL earlier questioned portions such as the one that would put up a ministerial government in the Bangsamoro under an existing unitary presidential system.

The government's implementing panel is chaired by Irene Santiago while MILF side is headed by Mohagher Igbal, its chief negotiator during the peace talks.