A university professor facing murder charges from a 1980 bombing in Paris has been denied bail as he awaits hearings for extradition to France.

Hassan Diab has been in custody since his arrest Nov. 13 at the request of French authorities, who allege he was involved in the explosion that killed four people outside a synagogue in the French capital.

Canadian government lawyers had argued Diab would be a flight risk if he was allowed to go free before the extradition proceedings begin, likely next month.

Ontario Superior Court Justice Michel Charbonneau agreed, saying in his ruling Wednesday that "all the ingredients exist to spur a flight in this case."

Charbonneau said evidence in the bail hearings last month -- including extensive trips in and out of Lebanon from 1998 to 2006 and a history of residence in several countries -- suggests Diab "does not have any real ties anywhere."

The judge added that evidence provided by the French government, while circumstantial, will "more likely than not" meet the threshold to justify extradition.

He said he was not basing his decision to keep Diab in custody on the basis of the information provided by the French government -- which could eventually could "fall like a house of cards" in a trial -- but noted the burden of proof for extradition is lower.

French police affidavits claim evidence links Diab, 55, to the purchase of a motor scooter that was used to place the explosives in front of the synagogue. French authorities allege he belonged to a terrorist group backing an independent Palestinian state at the time.

But Diab's Quebec-based lawyer, Rene Duval, argued it was a case of mistaken identity and said Diab was attending university in Beirut, Lebanon, at the time of the attack.

Diab has been a part-time sociology lecturer at Carleton University and the University of Ottawa for the last year.

His wife, Rania Tfaily, is a full-time professor at Carleton University and offered to put up bail and vouch for Diab's release conditions.

But Charbonneau noted the relationship between Diab and Tfaily, 24 years younger than Diab, was unstable and had only begun in 2006 after Tfaily obtained her position at Carleton University.

The judge noted Diab moved from Tfaily's Ottawa condominium last year into an apartment sublet in Gatineau, Que., and the pair gave contradictory reasons for the separation as well as the amount of time Diab later spent at Tfaily's residence.

Charbonneau also said Diab's failure to report the loss of his passport in 1981 for nearly two years "suggests he may have familiarity with forged documents." Part of the French evidence centres on the lost passport, which Italian police found on a man they arrested in 1981.

A Quebec judge in Gatineau will hear a request Thursday for the transfer to French authorities of evidence and material the RCMP seized from Diab's apartment when he was arrested. France has until Dec. 28 to formally request extradition, and hearings to decide whether he should be sent to France are likely to begin in late January or February.

The judge hearing the extradition case must be convinced a jury of reasonably informed Canadians could find Diab guilty based on the evidence France has provided.