ATHENS (Reuters) - Greece will start dispatching key information on the EgyptAir crash to Egyptian authorities on Wednesday, including data from the airliner as it flew through Greek airspace moments before disappearing, a source close to the probe said on Tuesday.

"We will start sending the main data from tomorrow, including the radar tracking and the conversation with controllers," one source who requested anonymity told Reuters.

Sixty-six people are thought to have died when the EgyptAir Airbus plunged into the Mediterranean 290 km north of Alexandria on a Paris to Cairo flight on May 19. The aircraft dropped off radars 10 minutes after leaving Greek airspace and entering Egyptian airspace.

The source close to the probe, and a second defence ministry official, said Greece stuck by its account that the plane had lurched violently in mid-air before it disappeared from radar screens. There has already been an exchange of information with Egypt, the sources said.

Egyptian authorities said they did not see the plane swerve and lose altitude before it vanished from their radars.

Greek Defence Minister Panos Kammenos last week said the aircraft took a sudden 90 degree turn, before flipping 360 degrees in the opposite direction and plunging from a cruising altitude of 37,000 feet to 15,000 feet, then vanishing.

"The picture we have off our radars is what the minister announced...we insist on that," the defence official said.

The plane and its black box recorders, which could explain what brought down the aircraft, have not yet been detected. Egyptian officials have said it is too early to draw any conclusions on what may have caused the crash.

Asked about widespread speculation of an explosion, the source close to the probe said: "To be honest, I'm not an expert on this issue...the aircraft debris is too small in number for us to say why the plane crashed."

(Reporting By Lefteris Papadimas; writing by Michele Kambas)