Thai jet explosion 'not caused by bomb'

US investigators believe an explosion that destroyed a Thai Airways jet last month may have been caused by an exploding fuel tank.

It had been previously thought the blast had been caused by a bomb.

Thailand accepted the findings but would continue its own investigation until the U.S. report was completed and made official, said the Thai prime minister.

"The initial report from the U.S. has shown that the plane explosion was an accident," Thaksin Shinawatra told reporters.

The Thai Airways Boeing 737-400 exploded March 3 as it sat by a gate at the domestic terminal of Bangkok international airport, half an hour before Mr Thaksin, his son and 147 other passengers were due to board a flight to the northern city of Chiang Mai. A flight steward was killed and seven airline staff were injured.

On Tuesday, the National Transportation Safety Board, the US government agency that investigates transportation accidents, said that Thai and American bomb experts had found "no physical evidence of a bomb" to date.

High energy explosives were initially believed to be present, but none were found when traces of chemicals had been sent to the FBI to be tested on equipment more sensitive than that available in Thailand, said a statement issued by the NTSB in Washington, in conjunction with the Thai government.

Mr Thaksin said that although Thai investigators thought they had found traces of RDX explosive, it had been identified as such because of a laboratory error.

RDX, also known as cyclonite, is a chemical component of a plastic explosive.

"Even though we said earlier that the explosion was sabotage that was not final. We have to accept the result of the scientific tests," Mr Thaksin said.