Malaysia today said that a ceasefire between Muslim separatist rebels and government soldiers which it is helping monitor in the southern Philippines had not collapsed despite clashes in which 21 people died.

Thirteen rebels and eight government soldiers were killed today as guerrillas from the Moro Islamic Liberation Front (MILF) attacked an army outpost on the island of Mindanao, violating a two-year-old ceasefire.

"We don't consider it as a breakdown of the ceasefire. It could be isolated incidents," Deputy Prime Minister Najib Abdul Razak told a news conference.

"As far as we are concerned the ceasefire still remains," said Najib, who is also defence minister.

It was not clear how the clashes would affect peace talks scheduled to resume early this year but Najib said "the exploratory talks are continuing."

Unsanctioned attack

Some 50 security officials from mainly-Muslim Malaysia, Brunei and Libya are in the southern Philippines as part of an international team to monitor the ceasefire.

A Malaysian team was proceeding to the site of the fighting along with a joint government-MILF monitoring group, said MILF spokesman Eid Kabalu, who insisted that the attack was not sanctioned by the leadership.

Philippine army spokesman Colonel Franklin del Prado said the attack at Mamasapano, some 60 kilometers south of Cotabato city, was mounted by forces of MILF commander Abdul Rahman Binago whose brother, Fides Binago, leader of the Abu Sofia bandit group, was killed last week.

The attack indicated there was an alliance between the Abu Sofia, which has been involved in kidnappings and robberies, and the MILF, which had signed a ceasefire with Manila in 2002, he said.

Despite the signing of the ceasefire and the start of initial peace talks, sporadic clashes and military allegations that rebel commanders are sheltering members of the regional Jemaah Islamiah terror network have strained the peace process.