Parents have been advised against permitting children under the age of eight to use mobile phones.

Professor Sir William Stewart, chairman of the National Radiological Protection Board, linked heavy use to ear and brain tumours and concluded that the risks had been underestimated by most scientists.

David Hart, general secretary of the National Association of Headteachers, said there should be a ban on mobiles in schools.

Mobile phone companies claimed the report encouraged public concern without presenting new research.