Diplomat Richard Colvin lashed out Wednesday at government ministers and military commanders who have attacked his credibility and challenged statements he made about Canada's handling of Afghan detainees.

In a 16-page letter addressed to the Special Committee on Afghanistan, dated Wednesday, Colvin writes that some of the evidence presented before a parliamentary panel has been "inaccurate or incomplete."

"This supplementary written evidence to the Committee aims to clarify some of these issues," he wrote.

Canadian officials in Afghanistan sent seven reports during 2006 regarding detainee treatment, he claims, including one that repeatedly used the word "torture."

Additional reports from American and UN officials highlighted the risk that Afghan prisoners were being subjected to torture.

All of that information "had no visible impact on Canadian detainee practices," Colvin alleges.

He confirms he did not raise concerns about detainee abuse when Defence Minister Peter MacKay visited Afghanistan in 2006. But Colvin said he had only been in the country for 10 days at that point, and was unaware of the situation.

Responding to accusations that he was isolated from Afghan society and had to rely on second- or third-hand information, Colvin wrote that he travelled to several provinces, including Kandahar, and left the heavily protected embassy in Kabul "an average of twice a day -- probably 500 times in total."

Colvin also challenges claims by Conservative MPs that allegations of prisoner abuse were Taliban propaganda. Many of the prisoners in question were poor and illiterate, and not capable of mounting a sophisticated propaganda campaign, he wrote.

The letter referred to documents Colvin had already submitted to the committee, CTV's Roger Smith said.

"Really he's just pointing to information in his previously submitted documents and making arguments to defend himself against this attach from government ministers and generals," Smith said.

Colvin, who was once Canada's No. 2 official in Afghanistan, told the Commons committee last month that he warned the government in 2006 and 2007 about detainee abuse, but was ignored and told to edit his reports from the field.

The Harper government has repeatedly attacked Colvin's credibility in Parliament. More than 100 former ambassadors have signed a letter of protest over Colvin's treatment.