A French ship has picked up deep sea signals, thought to be from the black boxes of an EgyptAir jet that crashed last month.

Egypt's Civil Aviation Ministry said the La Place vessel detected the signals while searching the Mediterranean Sea where the plane is believed to have crashed last month - killing all 66 passengers and crew on board.

The search for the plane has narrowed to a 5km area in the Mediterranean.

A second ship, the John Lethbridge from the Deep Ocean Search firm, is also expected to join the search later this week, according to the committee investigating the crash.

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

The French ship is equipped with three deep-water devices known as Detector 6000s - which can detect the signals.

Some debris from the plane - including life vests, passenger belongings and pieces of wreckage - has been found, but the fuselage and black boxes are still missing.

Human remains have also been recovered, and a Cairo forensics team is carrying out DNA tests to identify the victims.

Egyptian authorities have said they believe terrorism is a more likely explanation than equipment failure, although no militant group has so far claimed to have downed the jet.

Some aviation experts have said the erratic flight path reported by the Greek defence minister suggests a bomb blast or a struggle in the cockpit.

Leaked data has indicated a sensor had detected smoke in a toilet and a fault in two of the plane's cockpit windows in the last moments of the flight.