Japanese scientists looking at patients with brain tumours say they can find no evidence to support fears that using a mobile phone boosts the risk of cerebral cancer.
In a study published on Tuesday in the British Journal of Cancer, researchers led by Naohito Yamaguchi compared the history of mobile phone use in 322 brain cancer patients with 683 healthy people living in Tokyo.
"We studied the radiation emitted from various types of mobile phones and placed them into one of four categories relating to radiation strength," said Yamaguchi.
"We then analysed how they would affect different areas of the brain, taking into account the organ's complex structure."
He added: "Using our newly developed and more accurate techniques, we found no association between mobile phone use and cancer, providing more evidence to suggest they don't cause brain cancer."
Previous studies into mobile phone use have thrown up conflicting findings, although the biggest investigation, covering 420,000 people and spanning in some cases more than a decade of phone use, failed to find a cancer connection.
Yamaguchi, from the Tokyo Women's Medical University, looked at patients with three types of brain cancer -- glioma, meningioma and pituitary adenoma -- which comprise around 85 percent of all brain tumours.
Several countries have guidelines such as advising the public to make shorter calls on mobile phones, use hands-free sets and let children only make essential calls in order to limit exposure to electromagnetic energy.