But the claim was denied by a spokesman for the country's main Muslim separatist group who charged that the attack had hit members of his organisation in violation of a ceasefire in place with the government.

Four MG-520 helicopters and two OV-10 planes blasted two houses in the marshlands of the southern province of Maguindanao on Friday, where about 50 Abu Sayyaf members were believed meeting with two Indonesian Jemaah Islamiyah members, said regional military chief Major General Raul Relano.

As many as 10 bodies were seen floating in the marsh waters after the attack but it could not be confirmed if they were Abu Sayyaf or Jemaah Islamiyah members, Relano said.

Two Huey helicopters tried to land troops in the area but could not touch down due to the deep water, he said, and this had forced the military to resort to airstrikes due to the difficulty of entering the marsh by foot.

One Huey helicopter was slightly damaged by return fire, the general said.

Relano said the attack in the central part of the main southern island of Mindanao did not violate a ceasefire in place between the government and the Moro Islamic Liberation Front (MILF), the main Muslim separatist group in the country.

Neither Jemaah Islamiyah or Abu Sayyaf are covered by the ceasefire between the government and the Moro Islamic Liberation Front sealed two years ago as part of a process towards forging an eventual peace accord.

However a spokesman for the front, Eid Kabalu, said that the attacks hit a gathering of MILF fighters and that no Abu Sayyaf or Jemaah Islamiyah members were at the site during the air strike.

One Moro Islamic Liberation Front fighter was wounded in the attack, forcing the rebels to fire back, he added.

Kabalu said the incident had been reported to a joint ceasefire monitoring committee and that an international monitoring team, made up of Malaysian and Brunei security personnel, would be asked to investigate the incident.

Military spokesman Lieutenant Colonel Bienvenido Pascual said the air strike was prompted by reliable military intelligence reports that Abu Sayyaf chieftains Khadaffy Janjalani and Isnilon Hapilon were meeting in the area with suspected Jemaah Islamiyah members led by Mike Usman.

The Muslim Abu Sayyaf, known mainly for kidnapping and bombing attacks against Christians and foreigners in the southern Philippines, has been linked by both Washington and Manila to the Al-Qaeda network of terror mastermind Osama bin Laden.

But Abu Sayyaf has not previously been closely tied to Jemaah Islamiyah, blamed for terror attacks in Southeast Asia such as the Bali bombings in October 2002 which killed 202 people.

The Abu Sayyaf had largely been based in the southern islands of Jolo and Basilan but a government crackdown by US-trained Filipino troops caused Janjalani and other top leaders to seek refuge in Sultan Kudarat province, adjacent to Maguindanao.

Jemaah Islamiyah is considered the regional chapter of Al-Qaeda. The government has said that at least four Indonesian Jemaah Islamiyah members are hiding in the southern Philippines.

While some defence officials have accused rebel commanders of sheltering Jemaah Islamiyah members in violation of the ceasefire, the Moro Islamic Liberation Front has consistently denied this.