Bangkok  - A Thai protest leader who survived an assassination attempt said Sunday he believes he was attacked by soldiers who were assigned to silence him because he knows too much about the shady side of Thai politics.

Sondhi Limthongkul, leader of Thailand's "yellow-shirt" movement that helped topple the government three years ago, spoke in his first news conference since the April 17 attack, in which his car was ambushed by gunmen in pickup trucks firing M-16 and AK-47 assault rifles.

"I am certain that soldiers were behind this assassination attempt," Sondhi said.

He offered no proof but listed factors that he said backed his argument, including the attackers' use of "weapons of war" and the way they positioned themselves during the shooting. "It was obviously the position of well-trained soldiers," he said.

Army spokesman Col. Sansern Kaewkamnerd said he could not comment on Sondhi's accusations until seeing the official police report on the attack, which will only be completed after the investigation wraps up.

Sondhi's supporters earlier said they suspected army involvement in the attack, which stunned Thailand. The army chief confirmed that bullets found at the scene of the shooting were issued to a particular military division, and said an investigation was under way to determine how they were "leaked."

"Those who were capable of doing it knew that senior officials would turn a blind eye to them," said Sondhi, who received 43 stitches in his head after doctors removed bullet shards from his skull. His driver was seriously wounded and an aide in the car was also hurt.

He did not say who he believed ordered the attack, or what information he had that would prompt anyone to want him dead.

Police have yet to make any arrests in the shooting, which they say involved at least five attackers, but Sondhi said he counted 10. Police said at least 84 bullet casings were found after the shooting.

Sondhi said he didn't believe that all closed-circuit traffic cameras in the area could have been broken that day, as officials have said. He also questioned how the attack could have been carried out while Bangkok was under a state of emergency with military stationed in the area of the shooting. The attack came after rioting in the capital led by a rival protest group.

Sondhi, an outspoken media tycoon and founder of the People's Alliance for Democracy, led protests that paved the way for a 2006 military coup that ousted former Prime Minister Thaksin Shinawatra for alleged corruption and abuse of power. He resumed protests to bring down two successive governments led by Thaksin allies.

Sondhi's alliance has proposed a new system for Thai politics that it claims would root out corruption. He said that military officials and politicians associated with "the old power" see his campaign as a threat.

"When there is a change in society, people who stick to the old interests lose their benefits and they will provide resistance," Sondhi said. "Resistance in a society like Thailand comes in the form of violence, bloodshed."