Amnesty International Canada has joined opposition members in calling for a public inquiry into the issue of Canadian troops transferring detainees over to Afghan authorities, a situation that critics say puts prisoners at risk of being tortured.

Alex Neve, the secretary general of Amnesty International Canada, said an inquiry is necessary to get to the bottom of a controversial issue that the government claims has been overblown by inaccurate reports.

"The government's insistence that torture concerns are groundless is now beyond preposterous," Neve said at a press conference in Ottawa on Tuesday morning.

"Ministers seek to attack the credibility of an accomplished diplomat and make absurd suggestions that torture only becomes a concern if it is somehow witnessed firsthand," he said.

"At the same time, their own secretive decisions to occasionally suspend torture clearly indicate that the risk is very real."

Speaking for the first time on the controversy, Prime Minister Stephen Harper brushed aside the explosive allegations.

"The fact of the matter is that whenever Canadian diplomats or Canadian military officials have concrete evidence, substantial evidence, of any kind of abuse, they take appropriate action," he said.

The B.C. Civil Liberties Association has also joined calls for a public inquiry.

Both groups have written to the government requesting an inquiry and have both been at the forefront of the torture issue for years.

In 2007, they filed a court case demanding a judicial review of the actions of Canadian Forces regarding the prisoner transfers in Afghanistan.

The torture issue has again become front-page news, after former diplomat Richard Colvin told a House of Commons committee that he warned officials about torture in Afghan jails.

Political commentator L. Ian MacDonald told CTV News Channel that while the government could potentially pay a political price in the House of Commons, the public may view the detainee issue differently.

"I think if you were to take a poll down at Tim Horton's, people would say: 'Actually, the Taliban are the guys trying to kill our guys, so we're not too concerned about them,'" MacDonald, also the editor of Policy Options magazine, said during an interview from Toronto, acknowledging that it is unknown how many detainees were Taliban supporters or even civilians.

MacDonald said it is doubtful that a public inquiry will proceed, though the special committee that heard from Colvin is free to go "wherever it wants."

"The problem with our committee system is that it's very weak -- they don't have staff, they don't have commission counsels, they don't have directors of communications, they don't have people who can do forensic work for them. And so committees tend to be fishing expeditions," he said.

With files from The Canadian Press