Three American soldiers were confirmed killed and four are still missing when an army helicopter, carrying 10 crew, crashed early yesterday in the sea off central Philippines, the military said.

"Fishermen have rescued three crew of the ill-fated MH-47 Chinook which has the capability to fly at night," said Colonel Michael Manquiquis, military spokesman in the central Philippines. American and Filipino troops are taking part in the war games in the area.

The fishermen, who were near the site when the incident happened at 2.30am, seven nautical miles southeast of Zamboangita Point in Negros Oriental, central Philippines, managed to fish out two American soldiers alive, Manquiquis said.

Another American soldier was rescued by the Philippine coast guard, the Philippine Navy, Air Force and American forces. The U.S. has sent a P-3 aircraft and C-130 plane for the rescue operation.

The helicopter carried two pilots and eight from the U.S. Army.

The ill-fated helicopter took off with another helicopter from Basilan on the way to Mactan, Cebu City, central Philippines. One of the helicopters, with tail number 42, crashed, several minutes after take off from Mactan, for Basilan.

"Fishermen in the area heard a loud explosion. Some newsmen and fishermen said the helicopter was on fire as it plunged into the sea," a radio report said.

The first confirmation of the incident came from Major Noel Detoyato, spokesman for military forces of the southern command.

Negros is on the west side of Cebu City, near the Mactan Air Base, another area for the U.S.-Philippine war-games. It also serves as a base for supplies.

"We leave it to the Armed forces to announce the names of those killed. They will not do this until the families of the victims have been informed," said Defence Secretary Angelo Reyes.

"It was either due to systems failure or pilot error. There was no sabotage and no hostile fire. We don't expect it to have an effect on the war-games. The exercises will continue. We all know that there are always risks involved in military exercises including accidents such as what happened."

The U.S. military spokeswoman Major Cynthia Teramae shared the same sentiment.

"Despite the helicopter incident, the U.S. is committed to continuing the training of its Philippine counterparts," said the U.S. embassy spokeswoman Karen Kelly.

The U.S. Army Colonel David Maxwell, who heads the 160 American soldiers deployed in Basilan, said: "Everything the military does is potentially dangerous. There is always risk."

Up to 660 U.S. troops, (160 in Basilan), and 3,800 Filipino soldiers are participating in the six-month U.S.-Philippine war games operations in Basilan, Zamboanga City on the southern island of Mindanao and at Mactan Air Base in central Philippines.

The U.S. force will only observe and train local troops and will not engage in combat with the Abu Sayyaf, the U.S. and the Philippine governments said, but the American troops in Basilan are armed and authorised to return fire when attacked.