And those using phones in the countryside may be even more at risk – because handsets give off more radiation in areas with poor coverage.
Experts linked mobile use to cancer of the paratoid salivary gland – located close to where a phone is held to the ear.
They studied 500 patients with this kind of tumour then compared their mobile use to that of 1,300 healthy people.
Those who used their phones for a few hours a day were found to be 50 per cent more likely to suffer from the disease.
Lead researcher Dr Siegal Sadetzki, of Israel’s Tel Aviv University, said: “The study has given us an indication that cell phone use is associated with cancer.”
She called for more research into the effect of mobile usage on mouth cancer rates.