Germanwings Flight 4U9525
Debris from Flight 4U9525 which smashed into the French Alps despite the captain's desperate attempts to save his passengersReuters

French military police said they have wrapped up an operation to recover debris from the crash site in the Alps where a Germanwings plane smashed into the mountainside.

Co-pilot Andreas Lubitz, 27, locked himself into the cockpit of the Airbus 320 and crashed it into the side of a mountain on 24 March, killing all 149 passengers and crew on board.

Collecting the wreckage of Germanwings plane 4U9525 took more than two weeks and a police source said pulverised fragments of the Airbus A320 were being stored in a hangar near the crash site.

"The process of collecting all the parts of the wreck has been completed, now we are entering the phase of decontamination", gendarmerie-captain Benoit Zeisser said on 20 April in the French village of Seyne-les-Alpes.

Four tonnes of kerosene in the Alps

Clean-up, or decontamination operations are now set to start but are expected to be a much longer process, according to local authorities.

First, experts have to analyse which parts of the soil were contaminated by toxic substances.

Lufthansa's spokesman Carsten Hernig, who is tasked with the clean up and restoration of the crash site, told Le Figaro there were about four tonnes of kerosene on board the plane.

"Our goal is to complete all the works before winter comes, because afterwards the snow will make any operation impossible," he said.

According to a Sunday Times report, the European Commission is preparing legal action against Germany over aviation safety shortcomings that may have been a factor in the suicide crash of the flight 4U9525 into the Alps.

In March, the EU's aviation safety agency tightened its safety recommendations and urged all airlines to always have two people inside the cockpit of a flying aircraft.