A French court Friday ordered a new probe into evidence allegedly linking a Lebanese-Canadian academic to the 1980 deadly bombing of a Paris synagogue before deciding whether to put him on trial.

On Friday, the appeals court said it would grant an anti-terrorist investigating magistrate until February 15 to further analyse a handwritten hotel registration form, which prosecutors claim was filled out by Hassan Diab, the only identified suspect in the case.

Diab, 64, was extradited from Canada to France in 2014, but then released earlier this year after French magistrates ruled evidence against him was "not convincing enough" to hold him.

Prosecutors had appealed the decision and the Paris court had been expected to decide on Friday whether to drop all charges or proceed with a trial.

Prosecutors and defence lawyers have already long haggled over results of previous handwriting analysis carried out on five words left on a hotel registration form.