The Bloc Québécois has halted a proposed wide-ranging investigation by federal MPs into the handling of Taliban prisoners by Canadian soldiers, but says questions about possible torture will be pursued on another front.

Liberal defence critic Ujjal Dosanjh tabled a motion before the Commons defence committee to probe allegations that captured fighters were handed over to known torturers in the Afghan prison system.

The committee met behind closed doors Tuesday, but a Twitter posting by Dosanjh said Bloc MPs halted the motion, which needed the support of all opposition parties to succeed.

A second, separate bid to launch an investigation will come before a special Commons committee on Afghanistan.

The all-party committee charged with overseeing the mission will consider two opposition motions Wednesday. One tabled by the NDP asks to call several witnesses, including a former diplomat whose warnings about torture early in the Kandahar mission appear to have been ignored.

The other comes from the Bloc Québécois.

'Wrong committee'

The Bloc's defence critic, Claude Bachand, said there is a train wreck of investigation demands before Parliament, and his party believes unanswered questions about prisoners are best put before the special committee.

"Mr. Dosanjh tabled [the motion] at the wrong committee and his motion was shot down," Bachand said.

But aside from procedural wrangling, Bachand said he believes the special Commons committee is better suited to get to the bottom of the issue.

"We'll have the complete latitude of inviting who we want as a witness," he said.

The Bloc's motion specifically asks for an investigation of the procedures related to the transfer of prisoners.

After question period, Dosanjh accused the Bloc of being in league with the Conservative government, which has been blamed for allegedly stonewalling a third, separate commission investigation into what military police may or may not have known.

"It appears to me that they don't want as wide-ranging an investigation as we had proposed," Dosanjh said. He called Bachand's reasoning "hogwash."

Was there a coverup?

At issue is whether the Tory government ignored or covered up reports early in the mission that apparently warned of prisoners being tortured in Afghan jails.

Defence Minister Peter MacKay promised this week to find out why diplomat Richard Colvin's warnings were not shared with senior ministers, including the prime minister.

He faced a renewed attack in the Commons on Tuesday from all three opposition parties, who say they find it hard to believe the politicians were kept in the dark about such serious human-rights allegations for over a year.

Colvin filed two critical reports, which were circulated widely in both the Foreign Affairs and Defence departments in mid-2006, almost a year before the government conceded there was a problem with the handling of prisoners.

When published allegations of abuse surfaced in the spring of 2007, the Tory government denied hearing any credible prior reports from Canadian officials.

MacKay suggested too much emphasis was being placed on Colvin's warnings.

The minister said after question period there are "hundreds, if not thousands, of documents, reports, memos and advice that come through all departments."

"The fact that one report or a series of reports weren't read by a minister or deputy minister shouldn't come as a surprise to anyone."

Although it deals extensively with the prisoner controversy, retired chief of defence staff Rick Hillier's new memoir doesn't say whether he saw Colvin's reports.

The former general said the government was kept fully advised of the explosive issue, but his references relate to events in 2007 — long after the issue surfaced publicly.