Rescue teams were tonight searching for the burning wreckage of a helicopter that crashed in the Thai jungle close to a US military training base.

Thai military chiefs said they do not believe the aircraft was from the domestic force. It was seen crashing in a mountain in Rayong, eastern Thailand, at around 6.35 p.m. local time.

Emergency services raced to the scene and battled to find the wreckage through the steep, dense woodland. The blaze later died down, making it even harder to see though the low light.

The area is around 20km from the U-Tapao Airport used by the US military each year for their Cobra Gold training exercises. This year's event is due to start on February 25.

Thai Navy spokesman Vice Admiral Prachachat Sirisawat said: ''We do not believe that this aircraft was from the Thai army, Navy or Air Force. Usually they do not have permission to fly at night.

''We need more time to confirm where the aircraft is from.''

The helicopter came down in the Huai Pong district, which is around 20km from the U-Tapao Airport. The Cobra Gold exercises take place in Rayong province.

Witnesses said they saw a ''small aircraft'' followed by an ''explosion and flames''.

Thanathorn Srinak, head of the Office of Disaster Prevention and Mitigation, Rayong Province, said it was not yet known what kind of helicopter had crashed.