The identification of human remains from the crash of Ethiopian Airlines Flight 302 is complete, the head of Ethiopia's police said late on Monday, six months after the plane nosedived into farmland outside the capital Addis Ababa.

The investigation was "very challenging," said Endeshaw Tassew, commissioner general of the Ethiopian Federal Police, in a statement broadcast on state television.

The Boeing 737 Max slammed into the ground with such force that only fragments of those who died could be recovered.