The Azerbaijan Airlines Embraer 190 crash-landed on Christmas Day as it flew to the Chechen capital Grozny in southern Russia.

The Brazilian air force said in a statement that the data from the recorders would be extracted and analysed as soon as possible.

These devices captured cockpit dialogue and flight data from the plane. They are being examined by the Aeronautical Accidents Investigation and Prevention Center, a unit of the Brazilian air force.

Azerbaijani President Ilham Aliyev has demanded that Moscow admit it mistakenly fired on the plane as it tried to make a scheduled landing at the Grozny airport.

Russia has not confirmed that one of its air-defence missiles hit the plane, though President Vladimir Putin told Aliyev in a phone call that the systems were active at the time and that he was sorry the incident took place in Russian airspace.

Russia said Grozny was being attacked by Ukrainian drones when the airliner approached to make its landing through thick fog.

Investigators from Kazakhstan, Azerbaijan and Russia have travelled to Brazil for the investigation, officials said.

The Brazilian air force said Kazakhstan is in charge of releasing the results of the black box analysis.