Richard Colvin, a former senior diplomat with Canada's mission in Afghanistan, appears before a House of Commons committee Wednesday in Ottawa. (CBC)

All detainees transferred by Canadians to Afghan prisons were likely tortured by Afghan officials and many of the prisoners were innocent, says a former senior diplomat with Canada's mission in Afghanistan.

Appearing before a House of Commons committee Wednesday, Richard Colvin blasted the detainees policies of Canada and compared them with the policies of the British and the Netherlands.

The detainees were captured by Canadian soldiers then handed over to the Afghan intelligence service, called the NDS.

Colvin said Canada was taking six times as many detainees as British troops and 20 times as many as the Dutch.

He said unlike the British and Dutch, Canada did not monitor their conditions; took days, weeks or months to notify the Red Cross; kept poor records; and to prevent scrutiny, the Canadian Forces leadership concealed this behind "walls of secrecy."

"As I learned more about our detainee practices, I came to a conclusion they were contrary to Canada's values, contrary to Canada's interests, contrary to Canada's official policies and also contrary to international law. That is, they were un-Canadian, counterproductive and probably illegal.

"According to our information, the likelihood is that all the Afghans we handed over were tortured. For interrogators in Kandahar, it was a standard operating procedure," Colvin said.

He said the most common forms of torture were beatings, whipping with power cables, the use of electricity, knives, open flames and rape.

Colvin worked in Kandahar for the Department of Foreign Affairs in 2006. He later moved to Kabul, where he was second-in-command at the Canadian Embassy. In both jobs, Colvin visited detainees transferred by Canadian soldiers to Afghan prisons. He wrote reports about those visits and sent them to Ottawa.

Colvin told the committee that the detainees were not "high-value targets" such as IED bomb makers, al-Qaeda terrorists or Taliban commanders.

"According to a very authoritative source, many of the Afghans we detained had no connection to insurgency whatsoever," he said. "From an intelligence point of view, they had little or no value."

Colvin said some may have been foot soldiers or day fighters but many were just local people at the wrong place at the wrong time.

"In other words, we detained and handed over for severe torture a lot of innocent people."

Colvin said they began informing the Canadian Forces and Foreign Affairs officials about the detainee situation in 2006 with verbal and written reports.

He said the warnings were at first mostly ignored, but by April 2007, they were receiving written messages from government officials that in the future not to put things on paper, but instead use the telephone.

Colvin mentioned David Mulroney, a deputy minister who is now the ambassador to China, as one of the officials who didn't want to hear the allegations.

Colvin said when a new ambassador arrived in May, the paper trail on detainees was reduced and reports on detainees were at times "censored" with crucial information removed.

He said all of these steps were "extremely irregular."

At the time, the government denied there were any credible allegations of torture.

But Tories questioned the validity of Colvin's sources, saying the information he received concerning the allegations were from second-hand and third-hand reports.

Colvin's testimony "seemed dramatic, but under questioning it was revealed to be filmsy, inconsistent, unreliable," Laurie Hawn, parliamentary secretary to Defence Minister Peter MacKay told CBC News. "[He] did not come across as credible."

While he didn't doubt Colvin's sincerity, "every time something has happened in that mission, we have taken action," Hawn said. "And that's evidenced by the improvements in the prison, the training we've done, money we've invested, the visits we've had organized with the various authorities there."

Colvin also said he only spoke to four detainees himself and he had no way to guarantee those prisoners had in fact been captured by Canadian troops.

He also admitted he never raised the allegations with ministers who travelled through Kandahar.