Muslim rebels waging a four-decade insurgency in the Philippines signed a historic pact with the government on Monday to end the conflict, but both sides warned the road to peace had only just begun.

President Benigno Aquino and Moro Islamic Liberation Front (MILF) chief Murad Ebrahim witnessed the signing of the accord, which aims for a final peace pact by 2016, in a landmark ceremony at the presidential palace in Manila.

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

Moro Islamic Liberation Front (MILF) chief Murad Ebrahim and other senior rebel figures emerged from their remote bases in the country's south to oversee the signing of an accord on Monday that outlines a roadmap for peace by 2016.

A "distraught" ex-Philippine president Gloria Arroyo was arrested at hospital on Thursday after being charged over a third case of alleged corruption during her time in power, authorities said.

An anti-graft court ordered her arrest after Arroyo was charged with plunder for allegedly stealing 366 million pesos ($8.8 million) in state lottery funds meant for charity programs, and spending the money on election campaigns.

Philippine officials and Muslim rebels resumed negotiations on Tuesday in the Malaysian capital in a bid to end a decades-old insurgency, amid hopes a roadmap for peace could be inked soon.

The four-day talks to halt the rebellion in the Philippines' troubled south, which has left more than 150,000 people dead since the 1970s, will discuss an accord outlining steps to finalize a peace pact, officials said.

More Western nations called on their citizens to be cautious in the Philippine capital on Saturday following a U.S. embassy warning a day earlier of an unspecified threat against Americans.

The warnings issued by the British, Canadian and Australian governments called on their citizens to be cautious amid fears they could get caught up in an attempted attack against Americans.

The United States issued a security alert for the Philippine capital of Manila on Friday, warning its citizens they could be the target of an unspecified attack.

The U.S. embassy in Manila released a statement calling for U.S. citizens to exercise extreme caution and consider canceling American gatherings in the sprawling and chaotic megacity of 15 million people.

Philippine authorities said Wednesday they had launched an investigation into the possible involvement of Catholic priests in the illegal trade of African ivory.

The inquiry came after a National Geographic report said church ownership of religious icons made from ivory was widespread in the mainly Catholic country of about 100 million people, officials said.

The Philippines is seeking to lure investment from Japanese companies that are being hurt by their country's bitter territorial dispute with China, a senior trade official said Wednesday.

Japanese firms in China have been targeted in recent weeks by demonstrators angered by the row over the Japan-held Senkaku Islands in the East China Sea, claimed by China, which calls them Diaoyu, forcing some to shut down.

About 3,000 Filipino Muslims burned U.S. and Israeli flags in a protest on Monday over an an American anti-Islam film that has sparked unrest worldwide.

The protesters in the southern city of Marawi gathered in a public square to express their anger at the movie, stamping on huge American and Israeli flags that they then set on fire.

Two al-Qaida-linked militants have been arrested in the Philippines over a 2001 kidnapping of a group of tourists in which two American hostages were murdered, a military official said Thursday.

The Abu Sayyaf members were arrested on the southern island of Mindanao on Wednesday following an 11-year manhunt for the killers of Christian missionary Martin Burnham and fellow American citizen, Peru-born Guillermo Sobero.