Islamic militants planned to attack an Israeli airliner in Bangkok, the Thai prime minister said on Wednesday.
Terror suspect Hambali was captured in Thailand
But the plan was foiled when some of those behind it were arrested, Thaksin Shinawatra said.
"They confessed they aimed to destroy some Israeli planes here," he said.
Mr Thaksin's admission came a day after an Israeli television programme also claimed that Thai police had foiled a plot against Israeli aircraft.
According to the television report, a man was arrested at Bangkok's international airport, while allegedly filming the El Al airline counter.
In a subsequent raid on the man's home, police were said to have found details of a plan to attack Israeli airline passengers.
A senior Thai security official told Reuters news agency that a Malaysian man called Li-Li had confessed to the plot.
He was arrested in August, just a few hours before the capture of Hambali, who is accused of being the operations chief for Jemaah Islamiah (JI) - a group allegedly linked to al-Qaeda and blamed for last year's Bali bombings.
Hambali was arrested in Thailand and is currently in United States custody at an undisclosed location.
Mr Thaksin told reporters that the airport plot had prompted tighter security.
Deputy Prime Minister Chavalit Yongchaiyudh said on
Wednesday that security had been further tightened ahead of next month's Asia Pacific Economic
US President George Bush and other leading world figures are due to attend the meeting.
Earlier this week Mr Thaksin ordered state officials to reveal as little as possible about Thailand's security plans for the summit, to avoid panic and confusion.
"We don't need to tell the world we will take all trash cans off Bangkok streets or look inside all of them,'' he said.