Tuesday's blast was the country's worst terrorist attack in three years

The defence department said that he was identified as Muntazer Sudang, 23, a member of the Moro Islamic Liberation Front, or MILF, which has been involved in a long-running insurgency against the government.

Investigators said they had evidence that the bomb exploded prematurely.

On Wednesday, another Muslim separatist group, the Abu Sayyaf, claimed responsibility for the blast in Davao city on the island of Mindanao, but Manila dismissed the claim as propaganda.

The MILF, which has been fighting for a separate Muslim homeland in the southern Philippines for more than three decades, has denied responsibility.

The Philippines President, Gloria Arroyo, has proposed a peace agreement with the MILF.

But the rebels said they would not negotiate unless government troops withdraw from a guerrilla stronghold captured last month on Mindanao island.

At least nine people allegedly linked to the MILF are being questioned over Tuesday's bomb outside the arrivals terminal at Davao City airport.

It was the worst terrorist attack in the country for three years. One hundred and seventeen people were injured, and an American missionary was among the dead.

The airport bombing is the latest in a wave of explosions to hit the region - including a car-bomb at Cotabato airport last month, an attack in the market town of Kabacan and a series of sabotage attacks on power transmission pylons.

Fighting between the MILF and government forces continued on Thursday.

The military said four civilians were killed in Lanao del Norte province when MILF rebels fired mortar rounds at an army post, and one soldier was reported to have been killed and nine wounded when MILF rebels attacked an army position near Pikit in North Cotabato province.

US troops have been helping to train Philippines troops to combat Muslim rebels in the south.

A small number remain in the southern town of Zamboanga, following joint military exercises there last year, and more US troops are destined for the island of Jolo later this year.

There have been reports from Washington that the fresh deployment could have a wider, combat, role, but Mrs Arroyo on Wednesday appeared to rule this out.