Head teachers are angry at a 'lack of consultation'

Out of a total of 26,532 schools, 2,350 had at least one mast within a 50 to 200 metre radius.

All central London schools have a mast within 200m. Soho Parish School has 27 masts nearby.

There are no proven health risks, but the National Radiological Protection Board advises a "precautionary approach" to citing masts near schools.

Mobile phone companies said they did liaise with local communities about the citing of mobile phone masts.

'No consultation'

Rachel Earnshaw, head teacher at Soho Parish School said: "I think it's very worrying. We don't know what the long term effect of these masts may be."

This is evidence that self regulation isn't working Malcolm Noble, Secondary Heads Association

In 2001, shortly after the licences were awarded to phone companies allowing them to provide 3G - the high-tech 'third generation' of mobile phone technology in the UK -, the industry signed up to 'Ten Commitments' to ensure open, honest and transparent business dealings.

It pledged to consult with schools when 3G masts were due to be erected nearby.

The BBC Three survey found that there were 695 schools with 3G masts.

But of the 412 who responded to a survey, 314 said they had not been consulted about the erection of masts.

Government recommendations say that masts should not be put up too near to schools without them being consulted.

Malcolm Noble, of the Secondary Heads Association, told 3 Investigates: "Of course it isn't acceptable. This is evidence that self regulation isn't working."

However Vodafone said it had "worked very hard to make sure deployment teams and agents consult".

It said some of the researched sites did not require consultation because they were 3G upgrades on existing masts or installed before the rules came in. Others were run by another company that should have consulted on its behalf.

3 UK said it "takes these issues seriously and works to ensure there is transparency." T Mobile told the BBC that it "endeavours to provide information and engage with local authorities."