Greek defence sources have reported the discovery of two large plastic objects in the sea 80km south of Crete, just hours after an EgyptAir jet travelling from Paris to Cairo went missing with 66 people on board.

The Airbus A320 passenger jet was flying at 37,000ft when it disappeared on Thursday 16km after entering Egyptian air space, EgyptAir said.

The floating objects were spotted in the Mediterranean Sea near an area where a transponder signal was detected earlier, the sources said. Life jackets have also been seen in the area.

The plane made “sudden swerves” mid-air and plunged before dropping off radars in the southern Mediterranean, Greece’s defence minister said.

Sherif Fathi, Egypt’s aviation minister, said the possibility of a terror attack was “stronger” than a technical failure.

Flight MS804 disappeared from radar with 56 passengers and 10 crew members on board, EgyptAir said.

Francois Hollande, France’s president, said in a televised address that the aircraft crashed early on Thursday.

An informed source at EGYPTAIR stated that Flight no MS804,which departed Paris at 23:09 (CEST), heading to Cairo has disappeared from radar.

EgyptAir said Flight MS804 took off from Paris’ Charles De Gaulle Airport shortly after 11pm local time.

“At 4:26am, rescue teams affiliated with the Egyptian armed forces have received an SOS message from the emergency unit of the missing plane,” EgyptAir said on Twitter.

The AFP news agency said the Egyptian army later denied detecting a distress signal from the missing plane.