"Malignant brain tumour incidence and its associated death rate will be observed globally to rise within a decade from now, by which time it may be far too late to meaningfully intervene."

A malignant brain tumour was a fatal diagnosis in the vast majority of cases, he said.

The safest ways to avoid potential harm were to opt for hands-free mode while keeping the device more than 20 centimetres away from the head and only using cellphones in emergencies.

Enough evidence and technology were available for industry and governments to take "immediate steps" to reduce consumers' exposure.

Vodafone New Zealand spokesman Paul Brislen said research into radio frequency fields had continued for nearly 70 years, and more specific research into mobile phones for the past couple of decades.

"Expert scientific reviews conclude it is unlikely there are adverse health effects linked to mobile phones that comply with applicable safety standards."

Telecom spokeswoman Rebecca Earl said research on risks of electronic devices was issued regularly but was often contradictory.

Speaking by cellphone last night, New Zealand Cancer Society medical director Chris Atkinson called the study's results "interesting", but said local experts would have to consider them carefully for any correlation here.