Sir William Stewart, chairman of the Health Protection Agency, has called for an investigation into the health effects of Wi-Fi on children.

The call follows news that the Department for Education and Skills is to equip more schools with Wi-Fi systems to help children improve their computer skills.

Stewart has chaired two studies into the health effects of mobile phone use, reporting in 2005 that there was no clear proof that mobile phone radiation affected children's brains, but advising that the precautionary principle should apply.

His first report in 2000 recommended that mobile phone masts should not be placed near schools.

There is no evidence that Wi-Fi can have harmful effects when used as specified, but Stewart is reportedly concerned that children are more at risk since they have thinner skulls and nervous systems which are still developing.

Some European countries have already raised questions about the effects of Wi-Fi in schools.

The Austrian Medical Association is campaigning against such deployments, and local authorities in Salzburg have advised schools not to install Wi-Fi and are considering a ban.

Philip Parkin, general secretary of the Professional Association of Teachers, said: "I have concerns about the health of pupils and staff.

"I am concerned that so many wireless networks are being installed in schools and colleges without any understanding of the possible long-term consequences.

"The proliferation of wireless networks could be having serious implications for the health of some staff and pupils without the cause being recognised. I am not saying there is a danger, but I have enough concern to ask for it to be investigated."

Parkin added that he was writing to the UK Education Secretary to ask for a full scientific investigation.