All passengers and crew on the jet are thought to have died after it plummeted into a remote area and "disintegrated".

Recovery teams have been flown in by helicopter and one of the black box flight recorders - crucial in piecing together what happened - has been found.

The debris appeared to have been spread over a wide area. Pictures showed many fragments as well as a wheel and part of a fuselage thought to be from the aircraft.

The Airbus A320 plane was en route from Barcelona in Spain, to Dusseldorf, Germany, when it came down on Tuesday morning less than an hour into its flight at Meolans-Revels, between Barcelonnette and Digne.

A total of 144 passengers, including two babies, as well as two pilots and four cabin crew were on board the 24-year-old jet, operated by Lufthansa's budget airline.

Officials said flight 4U 9525, which took off at 10:01am (9:01am Irish time), had started descending one minute after reaching its cruising height.

It then plummeted from 38,000ft to 6,800ft in eight minutes before crashing.

French aviation authorities said the plane did not issue a distress call and had lost radio contact with air traffic controllers at 10:53am.

The company said it was working on the assumption that the crash was an accident and any other theory was "speculation".

There were believed to be 67 people from Germany on the aircraft, including 16 students and two teachers from the same school in the town of Haltern. The youngsters had been returning from a school exchange in Spain.

Weather conditions were calm at the time the plane came down but they later deteriorated with rain falling. US officials said they did not believe terrorism was involved.

Germanwings chief executive Thomas Winkelmann told a news conference the pilot had more than 10 years' experience, including more than 6,000 flight hours on A320s. He said the firm would do everything possible to establish the cause of the crash.