The pilots of an Airbus A320 screamed in terror as they struggled to cope with a sudden surge in power, moments before their test flight off the French coast ended in tragedy last November, New Zealand media said on Monday.

The cause of the crash on Nov. 28, which killed five New Zealanders and two Germans, is still not officially known as data from the plane's flight and voice recorders is still being analysed, broadcaster TV3 said in a report on its Web site.

But the data shows the plane experienced a surge in power as it was about to land at Perpignan in southern France, causing it to climb steeply before plunging into the Mediterranean Sea, TV3 quoted chief investigator Jean-Pierre Dreno as saying.

"First it goes up, and then it falls on its side before entering the sea," Dreno said, adding the cockpit voice recorder captured the pilots' screams as they struggled to regain control.

The plane had been leased by national carrier Air New Zealand <AIR.NZ> to German carrier XL Airways for the previous two years. It was being flown by two XL pilots on a test-flight prior to being returned to Air New Zealand.

Also on board were four Air New Zealand staff and an inspector from New Zealand's Civil Aviation Authority.

In a statement released on Monday, Air New Zealand said it was still not aware of the cause of the crash, and it had been informed that analysis of the flight data would not be complete for a number of weeks.

The A320 is a twin-engine, single-aisle airliner made by the Airbus unit of European aerospace group EADS <EAD.PA> that normally seats around 150 passengers. About 1,960 A320 aircraft are in service with airlines around the world.