OTTAWA — Extraordinary rendition, the U.S. practice of shipping terrorism suspects to foreign prisons, may be legal in some cases, says the Foreign Affairs Department.

Documents obtained under the Access to Information Act reveal an intense internal discussion among federal agencies about the "implications for Canada'' of the controversial U.S. policy.

Legal advice on rendition was prepared by the Justice Department, in consultation with Foreign Affairs, in late 2005 after it became clear American planes linked to the U.S. Central Intelligence Agency were passing through Canada.

Maher Arar, a Syrian-born Canadian detained in New York in September 2002, was bundled aboard just such a plane and transferred by U.S. authorities to a grim Damascus cell.

Under torture, Arar gave false confessions to Syrian military intelligence officers about involvement with the al-Qaida terrorist network.

A commission of inquiry concluded that erroneous information the RCMP passed to the United States very likely led to Arar's removal to Syria.

The second volume of the inquiry report on his case, to be released Tuesday, is almost certain to recommend stricter monitoring of the intelligence community.

Arar says he was a victim of extraordinary rendition, the U.S. policy of sending terrorism suspects to countries, such as Egypt and Syria, known to use brutal methods to extract information.

The United States insists Arar was legally deported -- not part of any rendition program.

But the rendition issue, and the possibility U.S. planes may be ferrying terrorism suspects through Canada, clearly generated some hand-wringing in official circles.

Records obtained by The Canadian Press under the access law show a 10-page federal legal opinion on the subject was distributed to several officials on Dec. 2, 2005.

The text of the document was withheld from release under provisions of the law that allow the government to keep legal advice under wraps.

Foreign Affairs spokesman Rodney Moore said although there is no agreed definition, extraordinary rendition is associated with the detention and transfer of suspects into the custody of other states without due process or other legal safeguards.

"Whether any particular rendition is lawful would depend on the facts of each individual case.''

Moore also said Canada strongly believes the fight against terrorism must be carried out in compliance with international law.

He declined to discuss the internal legal opinion.

A Foreign Affairs briefing note drafted in mid-December 2005 said the legality of extraordinary rendition "remains highly controversial.''

It said that if a person were seized in a foreign country without the knowledge or permission of that state, the practice would violate "the principle of state sovereignty.''

The government said earlier this year a review of dozens of alleged CIA aircraft landing at Canadian airports uncovered no evidence of illegal activity.

The matter, however, remains the subject of ongoing scrutiny in Europe, where investigators have looked into purported CIA prisoner transfers and allegations of secret prisons.

Alex Neve of Amnesty International Canada accused Ottawa on Monday of failing to "launch a thorough and comprehensive probe'' of the possible use of Canadian airstrips by planes involved in extraordinary rendition.

"Some of those same planes implicated in the European cases are known to have made use of Canadian airspace and airstrips,'' he said.

"Government officials are saying there's no reason for them to even raise this with U.S. officials. That's deeply disturbing.''

Janet Dench, executive director of the Canadian Council for Refugees, suggested the Canadian government position on the issue was rather blurry.

"They're kind of hoping that nobody looks too closely, really, at what is legal.''