Using a mobile phone may increase the risk of certain types of brain cancer in humans, World Health Organization (WHO) cancer experts said on Tuesday.

A working group of 21 scientists from 14 countries meeting at the WHO's International Agency for Research on Cancer (IARC) said a review of all the available scientific evidence suggested cell phone use should be classified as "possibly carcinogenic."

That classification could prompt the United Nations health body to look again at its guidelines on mobile phones, the IARC scientists said, but more research is needed before a more definitive answer on any link can be given.

The WHO had previously said there was no established evidence for a link between cell phone use and cancer.