Hanoi - A large unidentified flying object exploded over an island off southern Vietnam, and local officials said Wednesday they suspected it had been a military or civilian aircraft.

The explosion occurred Tuesday morning above Cua Can commune on Phu Quoc, a large island belonging to Vietnam just off the coast of Cambodia, according to Ngang Van Truyen, chairman of the commune.

"It was a huge explosion, and we thought at first that it was thunder," Truyen said. "But then we saw a 100-metre-long smoke trail in the sky and knew that it was the explosion of a flying object."

Truyen said people in the commune found six pieces of aluminum-like metal painted yellow-green on one side. The largest piece is more than 1 metre long and 50 centimetres wide. However, no markings or letters are found on the pieces.

"One of the pieces pierced the metal roof sheet of a house in the commune, but no one was injured," Truyen said. "We are searching the area to see if there are other pieces, or even bodies."

According to a military official of the district, who requested anonymity, there were no military planes operating in the area at the time of the explosion.

"We haven't identified what it is, but we suspect that it is a plane," the official said. "It could be either a military plane or a civilian plane, but I don't think it's a flying saucer."

According to Ngang Van Truyen, the metal pieces are curved, and no noise had been heard before the explosion.

Several of Vietnam's government-controlled newspapers Wednesday reported the incident, but none had any further information on the object, which suggests that it was not a Vietnamese military aircraft.

Recent accidents involving Vietnamese military aircraft, including the crash of a light transport plane in April that killed five pilots, have been openly reported in the Vietnamese press. (dpa)