PARIS (AFP, Reuters) - An Air France flight that was diverted to Montreal after an anonymous threat has resumed its route to Paris on Tuesday (Dec 8) after a security check determined the threat was unfounded.

Air France tweeted that its Flight 83 from San Francisco was back enroute to Paris after a brief stop in Montreal where a "full security search" confirmed a "false alert" following an anonymous threat.

The flight had touched down in Montreal just before midnight local time, the firm said.

"Local authorities will begin checking the plane, passengers and baggage," Air France said in a statement to AFP. "An investigation will be carried out by the authorities to identify the origin of the alert," added the airline, which apologised for the "inconvenience and delay" to its passagers.

France has been on high alert since an extremist rampage in Paris on Nov 13 in which 130 people died.

A flight to Egypt operated by Thomas Cook Group Plc's Condor unit made an unscheduled landing on Monday in Budapest after receiving a bomb threat.

Officers found no bombs on board the aircraft, which had departed from Berlin bound for the Red Sea resort of Hurghada, police said in an e-mail.