OTTAWA - Newly leaked U.S. documents claim a Mauritanian terror suspect being held at Guantanamo Bay was the leader of a Montreal-based al Qaeda cell that planned terror attacks in the United States.

The secret documents, released by WikiLeaks and posted on their website, also claim members of al Qaeda were recruited and trained at a Montreal mosque, where the terror suspect served briefly as an imam.

Mohamedou Ould Salahi arrived in Montreal from Germany on Nov. 26, 1999. He became the imam at the Al Sunnah Al Nabawiah Mosque during the month of Ramadan, replacing the previous imam, who had left for pilgrimage to Saudi Arabia.

He left Canada after CSIS and the RCMP began to question him about ties to Ahmed Ressam, the so-called "Millennium bomber" who planned to attack the Los Angeles airport.

According to the documents, Salahi met with Ressam four days after arriving in Montreal on Nov. 26, 1999 and had prior knowledge of the plot as well as contact with the extremists planning the attack.

The documents also claim that the 39-year-old electrical engineer recruited three of the Sept. 11, 2001, terrorist hijackers and facilitated their training.

Salahi has acknowledged joining the mujahedeen in its fight against the Soviet invasion of Afghanistan. But he says he had no role in the millennium bomb plot and denies any association with al Qaeda, the Taliban or their associates since 1992.

The leaked documents say Salahi and a number of his associates met frequently at a Montreal safehouse operated by a friend and former classmate Salahi met in Germany who was later arrested in Israel.

Salahi has tried unsuccessfully to obtain Canadian intelligence documents from interviews the RCMP conducted with him in 2000, which he claims could corroborate his claim of abuse at the hands of his American captors.

The Supreme Court has refused to hear his case while the Federal Court of Canada ruled last year that he is not entitled to the information because he is neither a Canadian citizen nor subject to legal proceedings in Canada.

He has been held at the U.S. prison at Guantanamo Bay, Cuba, for more than seven years.

An attempted prosecution was called off when questions arose about whether key evidence had been obtained by torture.

The documents, prepared by the U.S. defence department in 2008 and titled "JTF-GTMO Detainee Assessment," consider Salahi one of the most valuable sources at Guantanamo.

"Detainee still has useful information regarding extremist activity in North Africa, Europe and Canada, as well as information concerning the 11 Sept. 2001 terrorist attacks," the documents say.

Also among the documents dumped online by WikiLeaks is a detainee assessment that suggests another Guantanamo inmate acted as an informer for Canadian intelligence but continued to maintain his militant ties.

The 2008 assessment file says Adil Hadi al Jazairi Bin Hamlili acted as an intelligence source for both the British and Canadians because of his connections to members of various al Qaeda-linked terrorist groups.

But the document says after repeated interrogations, the Central Intelligence Agency concluded Hamlili "withheld important information" from the British and Canadians and was found to be a threat.

The document says Hamlili, an Algerian, was involved in a plot to attack a U.S. consulate in Pakistan and was possibly the leader of an extremist cell that carried out a string of bombing attacks against civilian targets in 2002.