Craig Murray, who was removed as ambassador to the central Asian state ruled by Islam Karimov after going public about his concerns, defied a Foreign Office ban to publish the internal Foreign Office memos on his website, www.craigmurray.co.uk.
A Foreign Office spokesman said Britain unreservedly condemns torture, but said it would be "irresponsible" for the intelligence services to reject out of hand information that might protect British citizens from a terrorist attack.
The documents published on Friday include memos to Foreign Office chiefs in which Murray expressed his concern over the use of "torture material".
In one memo, Murray notes that he was told by Sir Michael Wood, legal adviser to the Foreign Office, that it was not illegal to use information acquired by torture, except in legal proceedings.
Matthew Kydd, an intelligence officer, had told him that the intelligence services sometimes found such material "very useful indeed, with a direct bearing on the war on terror", he said.
Murray said that even after he alerted his bosses, they continued to use material allegedly gained under torture "on the grounds that the UK could not prove that individual detainees were tortured to extract information".
Murray wrote: "I have dealt with hundreds of individual cases of political or religious prisoners in Uzbekistan, and I have met with very few where torture, as defined in the UN convention, was not employed."
Uzbekistan has put more than 6000 political prisoners in squalid jails where dozens of people have reportedly died of torture over the past several years.
But the country emerged as a key US ally after the attacks in the United States in September 2001, although earlier this year it forced America to hand back a military base it had used there since 2001 for operations in neighbouring Afghanistan.