The study found no link between glioma, meningioma and pituitary adenoma, the three most common types of brain tumour, and length of mobile use.

The Japanese res­earch, published in the British Journal of Cancer, was the first to consider the effects of radiation levels in different parts of the brain.

It follows the findings of most earlier studies. But Cancer Research UK warned that the long-term effects of mobile phones are still unknown as they have only been in widespread use for little more than a decade.

It said it would continue to monitor them.

The researchers, led by Professor Naohito Yamaguchi, assessed levels of radiation in more than a thousand people in terms of the number of years since a mobile was first used.

They also inves­tigated the average hours spent on the phone each day and which parts of the brain were likely to be affected.

They compared the history of mobile phone use in 322 brain cancer patients with 683 healthy people in Tokyo and found regular use did not significantly affect their risk of getting brain cancer.

Until a conclusion on the long-term health effects of mobiles is reached, the British Government recommends that people keep their calls short. Children should make only essential calls.