The EgyptAir plane missing over the Mediterranean Sea made "sudden swerves" immediately after it entered Egyptian airspace then dropped 22,000 feet, the Greek defence minister says.

A child and two babies are among the 66 people on board the Airbus A320, which disappeared from radar early on Thursday morning local time.

An image from April 2014 of the EgyptAir plane that is missing over the Mediterranean. Photo: AP

Flight MS804 took off from Charles de Gaulle Airport in Paris at 11.09pm on Wednesday (7.09am AEDT), and was scheduled to land in Cairo at 3.15am on Thursday. However, it never arrived.

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Ten crew members are on board, as well as 56 passengers from 12 countries.

Most of the passengers are from Egypt, with 30 citizens on board, while 15 are from France, two are from Iraq, and Britain, Canada, Belgium, Kuwait, Saudi Arabia, Sudan, Chad, Portugal and Algeria have one passenger each.

French President Francois Hollande confirmed MS804 had crashed. Photo: Gonzalo Fuentes

The crew of 10 is comprised of the pilot and co-pilot, five cabin crew and three security staff.

Contact was lost with the plane when it was above the Mediterranean Sea, about 280 kilometres from the Egyptian coast.

Greek defence minister Panos Kammenos said the flight was south-east of the island of Karpathos when it made sudden "swerves" immediately after entering Egyptian airspace then dropped by 22,000 feet.

A distraught family member is comforted at Charles de Gaulle Airport. Photo: Michel Euler

"It entered Cairo FIR [flight information region] and made swerves and a descent I describe; 90 degrees left and then 360 degrees to the right," he said.

In brief remarks before a disability conference in Paris, French president Francois Hollande said the plane had crashed.

"The information we have managed to gather, the ministers, members of the government and the Egyptian authorities, confirm alas that this plane had crashed," Mr Hollande said.Mr Hollande said the French government's "thoughts and compassion and solidarity" is with the families of all those on board.

The head of the Greek civil aviation authority told CNN that the last contact with the plane and air traffic controllers was as the plane passed over Kea, near Athens.

When they attempted to contact the pilots again 10 miles before the plane left Greek airspace, they didn't get a response despite trying for one and a half minutes.

At a media conference in Cairo, Egyptian civil aviation minister Sharif Fathi said "the whole of Egypt" had been affected by the incident but refused to say the plane was anything but missing.

"I would like to use the phrase 'the missing plane' until we find the debris or until we are sure about the fate of the plane shortly," he said.

"There are rumours circulating left, right and centre and they contradict each other. So please let us stop speculations.

"That doesn't mean we can deny that there could be a terrorist act or a technical act."

Mr Fathi said the last contact between the plane and the control tower was at 2.30am local time. At 2.40, it disappeared off the radar, and at 2.50 there were unsuccessful attempts to reconnect with the plane to find out what happened.

The aviation authority has booked a hotel in Cairo for families of those on board the plane, and has offered free tickets to family members in Paris so they can come to the centre of operations in Cairo.

In the hours after the plane disappeared, distraught family members arrived at Cairo Airport and Charles de Gaulle Airport to find out more information.

Egypt and Greece launched their search from the plane around 200 kilometres south-east of the island of Karpathos.

A merchant ship captain earlier told media he had seen a "flame in the sky" in the same region.

with Reuters