Gen Anupong Paochinda said there were no secret interrogation centres
Thailand's army commander has denied allegations that Washington had a secret jail in Thailand where al-Qaeda suspects were interrogated.
It follows confirmation by the Central intelligence Agency that it destroyed 92 tapes of interviews with suspects.
The tapes - destroyed four years ago - were held in a safe in Thailand.
The footage is believed to have documented the interrogation and mistreatment of two leading al-Qaeda suspects at a Thai military base.
Allegations that Thailand was used to detain and torture al-Qaeda suspects have been around for years and they have always been emphatically denied, says the BBC's Jonathan Head in Bangkok.
But the campaign by the American Civil Liberties Union (ACLU) against the CIA to expose the treatment of those suspects has put Thailand back in the spotlight.
As the ACLU's case proceeds against the CIA, more details of Thailand's involvement in its so-called extraordinary rendition programme are likely to emerge, our correspondent says.
The Thai army commander, Gen Anupong Paochinda, has responded by stating that there are no secret interrogation centres in Udon Thani - an airbase from the Vietnam War era thought to have been used by the CIA.
But our Bangkok correspondent says there are other bases that could also have been used.
Another senior military officer told the BBC he could neither confirm nor deny the existence of the centres.
Thailand offered the use of its bases to the US in its campaign against al-Qaeda following the 9/11 attacks in New York.
In 2003 it helped capture Hambali, the head of al-Qaeda's regional affiliate, and was rewarded with the status of a major non-Nato ally.
But relations have been strained since the military coup in 2006 and friction over trade, says our correspondent.
If the allegations that al-Qaeda suspects were tortured here are confirmed, that will surely test that traditionally robust alliance, he adds.