A very large, 30-year study of just about everyone in Scandinavia shows no link between mobile phone use and brain tumours, researchers reported on Thursday.

Even though mobile telephone use soared in the 1990s and afterward, brain tumours did not become any more common during this time, the researchers reported in the Journal of the National Cancer Institute.

Some activist groups and a few researchers have raised concerns about a link between mobile phones and several kinds of cancer, including brain tumours, although years of research have failed to establish a connection.

"We did not detect any clear change in the long-term time trends in the incidence of brain tumours from 1998 to 2003 in any subgroup," Isabelle Deltour of the Danish Cancer Society and colleagues wrote.

Deltour's team analysed annual incidence rates of two types of brain tumour -- glioma and meningioma -- among adults aged 20 to 79 from Denmark, Finland, Norway, and Sweden from 1974 to 2003. These countries all have good cancer registries that keep a tally of known cancer cases.