The co-pilot of Germanwings flight 4U 9525 appeared to deliberately “destroy the plane”, French officials have revealed.

Speaking to media, Marseille prosecutor Brice Robin, said the co-pilot intentionally started a descent while the pilot was locked out of the cockpit.

Robin confirmed the hypothesis based on information from the ‘black box’ voice recorder recovered from the crash.

The co-pilot, named as Andreas Lubitz, was alive until the final impact, the prosecutors added.

There was “absolute silence in the cockpit”, Robin said, as the pilot fought to re-enter it.

“While he is alone, the co-pilot presses the buttons of the flight monitoring system to put into action the descent of the aeroplane.

“This action on the altitude controls can only be deliberate,” he explained.

Lubitz joined the low-cost subsidiary in September 2013, directly after training.

He had previously flown for 630 hours.

The Airbus A320 plane crashed in southern France on Tuesday with 150 people on board.

It has been on route from Barcelona to Düsseldorf.

Germanwings chief executive Thomas Winkelmann confirmed earlier 72 passengers on the flight were German citizens.

Officials in Spain said 51 of the dead were Spanish.

Other victims were from Australia, Argentina, Britain, Iran, Venezuela, the United States, the Netherlands, Colombia, Mexico, Japan, Denmark and Israel.