The Philippine government and the largest Muslim rebel group have signed a preliminary peace pact that outlines steps to end the conflict in the country's troubled south by 2016.

Chief negotiators from both sides signed the "framework agreement"on Monday, in a nationally televised ceremony at the presidential palace attended by President Benigno Aquino, Moro Islamic Liberation Front (MILF) chief Murad Ebrahim and Malaysian Prime Minister Najib Razak, whose country helped broker the deal.

The framework agreement calls for the establishment of a new autonomous region to be called Bangsamoro, or Muslim nation, in the southern region of Mindanao, by 2016.

The United Nations, the United States and other countries have welcomed the roadmap, achieved after 15 years of on-again, off-again negotiations between the MILF and various Philippine administrations, as a rare chance for peace.

However, the MILF's leadership, as well as independent observers and foreign governments, have warned the path towards peace remains littered with obstacles, and that Monday's signing does not guarantee an end to the conflict.

"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 news agency on Sunday before flying to the nation's capital.

Independence struggle

Muslim rebel groups have been fighting for full independence or autonomy since the 1970s in Mindanao, which they consider their ancestral homeland from before Spanish Christians colonised the country in the 1500s.

The estimated four to nine million Muslims are now a minority in Mindanao after years of Catholic immigration, but they remain a majority in some areas.

Muslims would be a majority in the planned new autonomous region.

The conflict has left huge areas of Mindanao, a resource rich and fertile farming region covering the southern third of the Philippines, in deep poverty.

It has also led to the proliferation of unlicensed guns and political warlords who battle over fiefdoms, while smaller but more militant Islamic separatist groups have been able to create strongholds in lawless areas.

Most of the 150,000 people estimated to have died in the conflict were in the 1970s, when an all-out war raged.

A ceasefire between the MILF and the government in place since 2003 has largely kept the peace, but outbreaks of deadly violence have occurred over the past decade.

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.

That peace pact led to an autonomous region in Mindanao, but Aquino described it last week as a "failed experiment" because of massive corruption and worsening poverty there.

The planned new autonomous region would replace the old one.

Obstacles to peace

Fresh attacks by the MNLF or small Islamic groups who still want independence are among the potential obstacles to the peace process.

Another is potential opposition from Catholic politicians and business leaders. The nation's parliament will have to approve the laws of the new autonomous region.

However, Aquino, who is one of the most popular presidents in the country's history, has invested a lot of personal political capital in pushing for an end to the conflict.

Experts have said that, unlike the unpopular Arroyo, Aquino may be able to convince the country's Catholic majority to support autonomy for Muslims.

The two sides have set 2016 as a deadline because that is when Aquino is required by the constitution to stand down after serving a single six-year term.

The formal peace talks have been held in Malaysia, and last week's announcement by Aquino that the "framework agreement" had been achieved came after months of intense negotiations in Kuala Lumpur.