Kuala Lumpur has asked for more help in the search for a Malaysia Airlines plane missing for more than a year, with France to send planes, boats and helicopters to scour the coast of a remote Indian Ocean island where debris washed up.

Investigators on the French-governed island of Reunion have collected a piece of a wing that Malaysia has said came from MH370, the first real clue in what has become one of the greatest mysteries in aviation history.

MH370, a Boeing 777, disappeared in March last year en route from Kuala Lumpur to Beijing with 239 passengers and crew on board, most of them Chinese.