OSLO: Police said a French student on a school trip to Norway was killed on Friday when he stuck his head out of a double-decker bus roof hatch while travelling at about 70km/h and slammed into a highway overpass.

The 15-year-old was flown by helicopter from the site of the accident, about 80km north of Oslo, to a hospital in the Norwegian capital, where he was pronounced dead.

Police spokesman Tom Midthaug said it was not clear why the boy opened the hatch. The bus was carrying about 60 French and Norwegian students.