MANILA (AGENCE FRANCE-PRESSE) - The head of the Philippines' main Muslim rebel group on Thursday (Feb 18) urged his followers to maintain a ceasefire with the government despite failure to pass a bill implementing a peace accord.

Moro Islamic Liberation Front (MILF) chairman Murad Ebrahim made the appeal in a statement carried on the group's Facebook page.

"In spite of the non-passage of the (bill), the MILF will continue to uphold the peace process and ensure that all the gains will be preserved," his statement read. "Our military forces will at all times maintain its defensive posture," he added.

Lawmakers this month failed to pass a bill that would have implemented a peace agreement forged between the 10,000-strong MILF and the government, which raised fears of fresh violence.

Philippine President Benigno Aquino, whose six-year term ends in June, had lobbied hard for the passage of the bill, which would have granted the nation's Muslim minority an autonomous southern homeland. But he was unable to muster enough support in the lower house of Congress to secure a vote before the legislature adjourned this month ahead of national elections in May.

The MILF signed a peace accord with Aquino's government in 2014 to end its struggle for independence, which began in the 1970s. Four decades of fighting in the south have left 100,000 people killed according to official estimates. Most political analysts say Aquino lost lawmakers' support for the autonomy bill after 44 police commandos were killed during a raid in the Autonomous Region in Muslim Mindanao, which is MILF territory, last year.

The commandos killed a Malaysian bomb maker on the United States' list of most-wanted "terrorists" but they were attacked by armed Muslims including MILF fighters.