An "inappropriate response" from stressed pilots was responsible for the 2009 crash into the Atlantic of an Air France plane flying from Rio to Paris that killed all 228 people on board, a new experts' report said.

The report, seen by AFP on Tuesday, was ordered by investigators. It said there was "an inappropriate response from the crew" after the plane's speed sensors malfunctioned.

The five experts said the "predominance of human factors in causing the accident and acting as contributory factors had been clearly established."

The crash "could have been avoided if the crew had taken appropriate action," they said.

In a 2012 report by France's BEA authority responsible for safety investigations into accidents or incidents in civil aviation, the June 1, 2009 crash was blamed on a mix of technical faults and human error.

Investigators had ordered the latest report, which was filed by the experts on April 30, following the BEA report.

The experts also fingered Air France, saying the pilots were not adequately trained to handle unusual situations like that when the speed sensors known as pitots malfunctioned.

"The distribution of tasks in the cockpit was not rigorously applied," they said.

A lawyer representing the families of victims said the latest report was "full of contradictions"

"The experts are just happy blaming the pilots while avoiding the key issue of technical failure," Yassine Bouzrou told AFP.

The Airbus A330 vanished at night during a storm. The black boxes were located by robot submarines after a search spanning nearly two years and costing millions of euros.