American pilots can call in the U.S. planes and helicopters for air strikes in case members of the Abu Sayyaf are seen at night in Basilan, southern Philippines, said National Security Adviser Roilo Golez.

The group is still holding a Filipina nurse and two American missionaries hostage.

American soldiers are training Filipino soldiers to use planes and helicopters capable of night-flying. Sources said surveillance flights have begun, but one of the helicopters crashed into the sea in central Philippines yesterday.

The plan is to do surveillance four four months with the use of the U.S. Navy and Air Force aircraft which are coming in from the U.S. bases in Kadena, Okinawa and Tokyo, Japan.

Information from the surveillance aircraft will be given to the Philippine Air Force to help the Armed Forces of the Philippines to crush the Abu Sayyaf in Basilan.

After four months of air surveillance, the U.S. soldiers will be deployed in Zamboanga City for a month-long training session. In the fifth month, they will return to Basilan as observers of Filipino soldiers who will patrol against the Abu Sayyaf.

At first, the information about the surveillance flights of the U.S. soldiers was classified, admitted Philippine Armed Forces chief General Diomedio Villanueva.

Basilan, the area where the Abu Sayyaf is believed to be hiding two American missionaries and one Filipina nurse, has been the centre of media scrutiny, compared to the war games to be held in nearby Zamboanga City and Cebu City, central Philippines.

Surveillance flights are being undertaken while the U.S. soldiers are being ferried from Cebu City to Basilan.

Some 80 of half of the 160 U.S. Green Berets are deployed in the jungle camps in Basilan. In the next 10 days, on March 4, all the Green Berets will be in Basilan.

"They are now in an observation phase of the training exercises which are to last for one or two weeks," said Brigadier Emmanuel Teodosio, Filipino co-director of the joint war games.

Sources said the U.S. and Philippine intelligence networks are very active in the exchange of information on members and organisations of suspected terrorists operating in the Philippines, Indonesia, Malaysia and Singapore.

The intelligence network is trying to find out the full extent of the operations of suspected terrorist organisation Jemaah Islamiyah (JI) in southeast Asia.

The two have been tracking the movement of the JI since Philippine authorities arrested suspected Indonesian terrorist Fatur Raman Al Ghozi in Manila's Quiapo district on January 15.

The Abu Sayyaf and the JI are suspected to have ties with the Al Qaida terrorist network of Saudi-born Osama bin Laden.

Meanwhile, the newly arrived U.S. Ambassador to Manila Francis Joseph Ricciardone recently expressed concern about the global reach of terrorism, adding the U.S. was giving "particular attention" to Southeast Asia.

Adds Our Correspondent in Basilan: American soldiers have been trying hard to be sweet, to befriend Christian and Muslim residents as well.

They have been walking side-by-side with Filipino soldiers to help the local Red Cross launch a medical mission, part of the ongoing Gentle Wind campaign in the war games areas.

They have been giving away medicines and milk formula to organisations, which are helping residents in Basilan. Many children, however, were disappointed because they expected to get candies. Adults expected to get cigarettes.

Five U.S. servicemen were not allowed to donate blood. Medical practitioners said the U.S. soldiers were under anti-malaria and anti-hepatitis medication. Sources said the doctors are worried that the soldiers might be HIV carriers. The U.S. government recently refused the Philippine-proposed mandatory HIV test for incoming U.S. soldiers.

"We'll try to help in some other ways. We will be here for six months," said Major Mark Gato, head of the U.S. delegation in Basilan.

Several American soldiers also worked as doctors. This has made them more close to the residents, many of whom are sickly, poor and have not tasted government services.