US marines are training a small group of their Philippine counterparts for action against Islamic militants holding two European Red Cross volunteers, a military official said Thursday.

The US is also providing intelligence assistance to track down the group, now holding out on southern Jolo island with hostages Eugenio Vagni of Italy and Andreas Notter of Switzerland, officials said.

"A select group of Philippine marines embarked on training with American marines in small unit operations to find, fix and fight the highly mobile and guerrilla-type skirmishes of the bandit group," said Philippine Navy spokesman Lt. Col. Edgar Arevalo.

He said that the Filipino marines would be used "as fresh soldiers to combat the terrorist Abu Sayyaf group" once they completed the six-week training.

The training was taking place at a seaside military base on Jolo, and involved around 100 soldiers and personnel, he said.

Meanwhile, on the main island of Luzon and in the eastern Bicol region, some 6,000 US forces joined 2,500 Filipino soldiers as part of two-week joint exercises.

Small numbers of US forces have been rotating over the years on Jolo, where Vagni and Notter have been in captivity since January 15. A third hostage, Filipina Mary Jean Lacaba, was released earlier this month.

"Outside of the actually taking part (in the war games), the United States continues to share intelligence with the Philippines on this," said US envoy Kristie Kenney, referring to the hostage crisis.

While the Philippines and the US are bound by a decades-old mutual defense treaty, foreign troops are prohibited from combat operations in the Philippines, Filipino military chief General Alexander Yano said.

Apart from "technical intelligence," Yano said, the Philippines may also need US help with medical air evacuations and airlifting of equipment and transport.

On Wednesday, the negotiating team on Jolo sent five Muslim clerics to the Abu Sayyaf camp in a last-ditch effort to convince them to hand over the hostages peacefully.

Yano said there had been no update from the intermediaries and declined to comment on the next move. He has, however, said troops can launch a rescue operation once given the go-ahead by hostage negotiators.

The Abu Sayyaf is a small group of self-styled Islamic militants blamed for some of the Philippines' worst terrorist attacks, including deadly bombings and kidnappings. The US government has listed the group as a foreign terrorist organization.

Two US hostages seized from an island resort in 2001 were killed while in captivity, one of them beheaded by the Abu Sayyaf.