The chances of developing a malignant tumour are "significantly increased" for people who use a mobile for ten years. The shock finding is the result of the biggest ever study by the International Agency for Research on Cancer, part of the World Health Organisation.

Scientists found a type of brain tumour called glioma is more likely in long-term mobile users

French experts analysed data from 13 countries, including Britain. They cross-referenced various types of tumours with mobile use . Researchers admit the cause is unknown, but it is thought radiation from handsets could be the trigger. Study chief Professor Elisabeth Cardis said: "To underestimate the risk would be a complete disaster."