Missing EgyptAir flight MS804 had reportedly been forced to make three emergency landings in the 24 hours leading up to crash.

The Airbus 320 is said to have been forced to turn around shortly after takeoff on three separate occasions after it's warning systems signalled an anomaly onboard.

The claims, made in French media, have since been denied by the Egyptian lead crash investigation committee.

A French soldier searches for debris from the crashed EgyptAir flight MS804 over the Mediterranean Sea

The airplane's onboard warnings system, Acars, went off shortly after take off from three airports where in the 24-hours before the crash, Euronews reports.

All alerts were reportedly investigated after emergency landings, with nothing found,

'We cannot presume to know know exactly what happened on board but it’s not entirely normal to turn around several times after a technical incident without finding anything,' Jean-Paul Troadec told TV channel France 3.

Mr Troadec added that 'Acars signals are emitted automatically only in the case of a malfunction. In normal mode they remain silent'.

The search zone for the crashed EgyptAir flight's black boxes has today been been narrowed to two kilometres (1.25miles) from five kilometres(3.1miles), a source on the investigation committee said.

The EgyptAir Airbus A320 crashed into the sea with 66 people on board during a May 19 flight from Paris to Cairo after disappearing from radar screens

This comes after French naval search vessel Laplace picked up signals believed to originate from one of the black boxes of flight MS804.

The Civil Aviation Ministry is citing a statement from the committee investigating the crash as saying the vessel Laplace is the one that received the signals.

The EgyptAir Airbus A320 crashed into the sea with 66 people on board during a May 19 flight from Paris to Cairo after disappearing from radar screens.

Locator pings emitted by flight data and cockpit voice recorders, known as the black boxes, can be picked up from deep underwater.

Investigators had been racing against time to find MS804's black boxes, as they only have enough battery power to emit signals for four or five weeks.

The recordings could help investigators determine the reason for the crash.

The plane was carrying passengers from different nationalities, with 40 Egyptians including the crew and 15 French nationals.

Egypt's aviation minister had initially said a terrorist attack was more likely to have brought down the plane, but a technical failure is also likely.

France's aviation safety agency has said the aircraft transmitted automated messages indicating smoke in the cabin and a fault in the flight control unit minutes before losing contact.

Egypt and France have signed agreements with two French companies specialising in deep water searches, Alseamar and Deep Ocean Search (DOS).

Picture on the official Facebook page of the Egyptian military spokesperson shows part of debris found by search teams looking for the EgyptAir flight

'Those two companies have complementary roles: the first is for locating the pings of the black boxes (the signal being emitted by the black boxes' beacon), while the second is for diving and recovering them' with the help of a robot, a source close to the investigation told AFP in Cairo, requesting anonymity.

'But the DOS specialised ship left the Irish sea Saturday and it will reach the perceived crash site only in around 12 days, after having the Egyptian and French investigators embark in Alexandria,' the source added.

The investigators are searching for the black boxes at a depth of about 10,000ft, some 180 miles north of the Egyptian coast.

Three of Alseamar's DETECTOR-6000 acoustic detection systems, which submerged can detect pings for up to 4,000 to 5,000 metres below sea level, have left the French island of Corsica to the crash site Thursday onboard 'Laplace', a French navy ship.

It will arrive at the perceived crash site 'Sunday, or Monday at the latest,' according to one of the sources.

'While we are waiting for the DOS ship, equipped for detecting the pings in deep waters, but more importantly the robots capable of descending up to 6,000 metres to recover the black boxes, we will not be wasting time as Leplace will be trying to locate them in the meantime,' said one of the sources.

The source added that after 12 days, 'there is a very good chance of recovering the flight recordings thanks to the combination of these two French companies.'