The leader of the Philippines' biggest Muslim rebel group is expected to arrive in Manila on Sunday for a historic visit aimed at ending one of Asia's longest and deadliest insurgencies.

Murad Ebrahim and other senior figures of the Moro Islamic Liberation Front (MILF) are scheduled to participate in the signing of an accord at the presidential palace on Monday that outlines a roadmap for peace by 2016.

The accord, announced by President Benigno Aquino a week ago, has won applause from foreign governments and the United Nations as a rare chance to end a rebellion that has killed an estimated 150,000 people since the 1970s.

However rank-and-file soldiers of the 12,000-strong MILF, as well as the groups's leaders and independent security analysts, have warned that many obstacles could still derail the peace process.

Ebrahim, an ageing warrior in his 60s who has spent most of his life in the southern Philippine region of Mindanao, will be making his first official trip as MILF leader to Manila and his first visit to the presidential palace.

"We feel honoured to be welcomed in Manila, but I must stress this is just the beginning of the peace journey," Ebrahim's deputy for political affairs Ghazali Jaafar told AFP by phone from the MILF's southern headquarters before departing for Manila.

Jaafar arrived in Manila around 4:00 pm (0800 GMT) Sunday, along with other MILF officials.

He said Ebrahim was to take a separate plane and arrive later in the day.

The MILF chief "feels relieved" that the roadmap for peace would be signed, Jaafar said, after 15 years of negotiations.

In a statement shortly after Aquino's announcement on the "framework agreement", Ebrahim had said the deal "lays down the firm foundations of a just and enduring peace formula".

"The forging of the framework agreement, however, does not mean the end of the struggle for it ushers a new and more challenging stage," he said.

Muslim rebel groups have been fighting for full independence or autonomy for four decades in Mindanao, which they consider their ancestral homeland from before Spanish Christians colonised the country in the 1500s.

The fighting has mired large parts of resource-rich Mindanao in poverty, and led to the proliferation of unlicensed guns and political warlords who battle over fiefdoms.

The estimated four to nine million Muslims are now a minority on Mindanao after years of Catholic immigration, but they insist they should be allowed to govern on their own and control Mindanao, which has fertile farming lands.

The MILF is the biggest and most important remaining rebel group, after the Moro National Liberation Front (MNLF) signed a peace pact with the government in 1996.

The peace deal with the MNLF led to the creation of an autonomous region that Aquino said was a "failed experiment" that led to corruption and even more poverty.

Underscoring the current fragile security situation in Mindanao, the army said Sunday that three soldiers were gunned down by Al Qaeda-linked Abu Sayyaf militants in a bid to goad fighting ahead of the deal signing.

The Abu Sayyaf is blamed for the country's worst terrorist attacks, and it is not included in the negotiations.

The document to be signed Monday will outline plans to replace that autonomous region with a new one in which the MILF will hold significant power.

Under the framework, the MILF will drop its bid for independence in exchange for autonomy covering several areas on Mindanao island, the southern third of the mainly Catholic Philippines.

They will have their own taxation and share of revenues from natural resources.

It's forces would be disarmed in stages, while the government retains powers in defence, as well as monetary policies.

A transition panel made up of members from both sides is to draft a "basic law" covering the autonomous region to be passed by the nation's parliament by 2015.

The people living in the proposed autonomous region would then need to ratify it in a plebiscite held before 2016 when Aquino is required by the constitution to stand down.

Malaysian Prime Minister Najib Razak, whose government hosted the talks, and OIC secretary general Ekmeleddin Ihsanoglu will attend Monday's signing of the peace pact.