OTTAWA - Concerns over the handling and safety of detainees in Afghanistan were relayed to Defence Minister Peter MacKay and other senior officials as potential "mission killers," a diplomat said Wednesday.

Cory Anderson, a former senior political adviser to Canada's provincial reconstruction team in Kandahar, said he briefed MacKay several times between 2007 and last year.

"We would talk about issues that we were concerned about in terms of what we would characterize as 'mission killers' -- and this was one of them," Anderson told MPs at a special committee studying the Afghan mission.

He said he had no specific allegations of prisoner abuse to pass on because before 2007 Canada had no way of tracking the people it handed over to Afghan authorities. However, there were general worries about torture.

Anderson said despite a lack of hard evidence of torture, senior civilians and military brass in Ottawa were "fully aware of the plausible risk of abuse" of prisoners handed over to the Afghan National Directorate of Security, or NDS.

He did brief officials, including MacKay, about the problems of the NDS, which he described as duplicitous and open to manipulation by politically powerful people behind the scenes.

"It's common knowledge amongst senior officials, civilian and military, the behaviour of the NDS when it comes to how they react to certain pressures placed upon them by tribal elders or people of influence throughout Kandahar."

He said in hindsight, it was probably a bad decision for Canada to work with the NDS in the handling of detainees.

Even though the present system allows for tracking Canadian detainees in Afghan custody and provides for unannounced spot checks of their condition, the NDS remains an unsavoury partner.

Canada would probably been better off to find another body to handle the detainees it captured, he said.

"I wish I would have been a little bit more vociferous trying to come up with alternatives, given the knowledge that we had about the NDS as an institution."

There were suggestions that the international force should set up its own prison, or explore ways for the Afghan army to handle them. These ideas came to nought.

Anderson added that he's given up any hope of changing the NDS.

"I'm not certain that there are any ways that we could potentially try and reform the NDS that haven't already been attempted," he said.

"I think that, given their track record ... in my specific experience and what I've learned from some of our allies, the prospect of the NDS being significantly reformed in one way or another is probably very slim."

Anderson said he had to choose his words carefully before the committee, because the Justice Department has been watching public servants testify.

He said he hadn't been specifically told what he might or might not say.

"The ability to speak frankly in a setting like this is made more difficult by interpretations by the ministry of justice on what actually pertains to be national security and operational imperatives," he said.

"What I've been told is that I, as a public servant, am still under the terms of any public servant and that is being determined by the ministry of justice, in my view, quite rigidly."