They've spent years trying to clear their names from any suggestion of terrorist ties. But a CSIS document leaked to Montreal's French-language newspaper La Presse now suggests why Abousfian Abdelrazik and Adil Charkaoui have been terrorism suspects for so long in the eyes of the federal government.

The La Presse report says CSIS intercepted a phone conversation between the two men in the summer of 2000. In the CSIS document the newspaper describes, the two men reportedly discuss a plot to blow up an airplane travelling between Montreal and France using explosives hidden in a keychain.

Lawyers representing the two men categorically deny their clients are involved in any terrorist plot, and said the information on which the report is based may not be reliable evidence.

"There's never been any criminal charges against Mr. Abdelrazik. Presumably this type of a conversation would attract at least some kind of criminal investigation or a criminal charge," said Khalid Elgazzar, one of Abdelrazik's lawyers. "The RCMP and CSIS have both confirmed that Mr. Abdelrazik is not involved in any criminal activity."

Elgazzar also suggested that the allegations are not entirely new.

In 2007, La Presse reported that Charkaoui and another individual, Hisham Tahir, were part of a plot to fly a plane into an unspecified target in Europe. The reporters of that story fought in court to protect their right not to reveal the source of their information.

Tahir has never been located by the media nor charged with any terrorism offences in Canada.

The documents on which La Presse has based both of its reports have never been disclosed to either Charkaoui's or Abdelrazik's legal team, nor made public in court proceedings. It's not known whether both La Presse reports are based on intelligence from the same intercepted conversation Charkaoui had, but the newspaper confirmed to CBC News that its two stories stem from different types of documents.

Abdelrazik's legal team believes a federal court judge may have reviewed this latest intelligence in 2007, during security certificate hearings at which secret evidence was presented about the federal government's case against Charkaoui. The ruling in that case said the information remains unproven.

"Is it hearsay? Is it double hearsay? Is it triple hearsay? We don't know," Elgazzar said.

Johanne Doyon, Charkaoui's lawyer, dismissed both the old and new allegations. "The federal court rendered a judgment in 2008 stating this allegation was in the file but it's not proven," she said.

Federal court judgments from 2009 ruled there was insufficient evidence to suspect Charkaoui of terrorism and lifted the strict conditions imposed by the national security certificate under which he was detained and monitored for six years.

Doyon said she was shocked to see this latest report surface. "This is not new at all," she said of the intelligence behind the story. "There is another purpose" for the leak, she suggested.

Elgazzar said the timing of this latest leak "is very suspect," coming as Abdelrazik fights to remove his name from the United Nations terrorism blacklist. "This appears to be an attempt to undermine his efforts to clear his name."

Immigration minister unsympathetic

Speaking to reporters Friday morning on a conference call from Thailand, where he is travelling on government business, Immigration Minister Jason Kenney would not comment on specific government intelligence about the two men.

However, he did say that "when the government takes the position that someone should be under a security certificate, or that a Canadian overseas is on the UN no-fly list because of suspected membership in al-Qaeda, when we take such positions it's not based on a hunch, it's not based on innuendo, it's not based on speculation. It's based on very robust intelligence and Canada only takes such measures against such individuals when it believes that they constitute a real threat to national security."

Kenney also had a warning for those who'd been working with Charkaoui and Abdelrazik to clear their names, or had gone "to the extent of treating such people as folk heroes."

"All I can say is that I hope those who form these political support groups for individuals who have been the focus of security certificates or similar extraordinary efforts on the part of government think very carefully about this," added Kenney. "I hope that people will realize that the government does not take these measures lightly, and that these measures are only taken on the basis of very compelling evidence that such individuals mean Canada harm and no good."

"If this was very robust evidence, presumably there would have been some kind of criminal charge that would have been laid. But of course there was none," Elgazzar said when told of Kenney's remarks. "So that in and of itself should tell you something about the veracity of these allegations and the source of this information."

Public Safety Minister Vic Toews would say only that the standard of proof differs in security matters and criminal cases.

Michel Juneau-Katsuya, a security analyst who used to work for CSIS, agreed that there's a difference between security intelligence and evidence gathered to prosecute a suspect in court.

"When you go to court, the bar is extremely high," Juneau-Katsuya said, adding that the government can use intelligence to intervene to protect the public, even if no charges are laid and the evidence is insufficient for a trial.

Juneau-Katsuya said this kind of a leak is rare, and troubling. "That it's [found] its way into the hands of the media and the general public, it's extremely problematic for the government. It talks about the integrity of the system."

"These sorts of leaks didn't happen under my watch," former public safety minister Stockwell Day insisted to CBC News on Friday. "Speculation can be rife on this."

Abdelrazik surveillance revealed

A total of six men would have been involved in the plane bomb plot discussed by Abdelrazik and Charkaoui, according to the CSIS document obtained by La Presse, which was written in 2004 to share intelligence with Transport Canada. At the time, Abdelrazik had been arrested by authorities in his native Sudan, but he was about to be released.

The Sudanese government has cleared Abdelrazik, who initially came to Canada as a refugee in 1990, of any charges.

Abdelrazik's journey back to Canada took years. He spent a year living on the grounds of the Canadian embassy in Sudan before the government was ordered to allow his repatriation in the summer of 2009.

CSIS had been monitoring Abdelrazik since 1996, the document reveals. The intelligence service allegedly found traces of explosives in an unspecified search of his vehicle in 2001. The document alleges Abdelrazik went to an al-Qaeda training camp in Afghanistan in 1997, and later went to Chechnya to fight the Russian army. It also suggest he knew Ahmed Ressam, the would-be "millennium bomber" who was apprehended trying to smuggle explosives into Washington state from British Columbia as part of a bomb plot.

Charkaoui has always maintained that Abdelrazik is only a casual acquaintance. He is suing the federal government for $24 million in damages.

Abdelrazik's lawyer Elgazzar says he spoke to his client after being contacted about the story in advance. "Of course he's disappointed," the lawyer said. "To have this kind of information recycled in the media is disappointing," Elgazzar added, in light of Abdelrazik's ongoing legal fights to clear his name from the UN terrorism watch list and sue for $27 million in damages from the federal government.

CBC News has not been able to see or authenticate the document on which the La Presse report is based. The Canadian Press reports that CSIS will not comment on its authenticity because of security concerns.