In the increasingly competitive mobile phone market, operators are racing against each other to build enough masts to complete their coverage of Britain.

BBC correspondent Charles Rhodes: "Parents fear for their children's health"

There could soon be as many as 14,500 transmitter masts across the country to cope with the ever growing number of people who use mobile phones.

At present 13.5 million people use a mobile phone, and it is estimated that within four years half the population will be using them.

Now local campaigns have been launched to try to get the masts removed from school roofs and residential areas.

They want Britain to follow the example of the USA and New Zealand, where permitted emission levels from transmitter masts have been reduced and exclusion zones have been created around hospitals, schools and residential areas.

School roof transmitter

Parents of children who attend St Margaret's Church of England Primary School in Manchester are concerned about the mast that was erected on the school roof during the last summer holiday.

Rick Walker is concerned about the health of his son

Parent Rick Walker is considering withdrawing his five-year-old son Owen from the school.

He said: "There have not been the long-term surveys into the health effects of long-term chronic exposure to low level microwave radiation.

"We are concerned the growing body of scientific evidence suggests that children are particularly at risk."

The school is tied into a long-term contract with the mobile phone company Orange.

To take it down St Margaret's would have to forego the lucrative rental, and also pay a heavy financial penalty.

Orange says the mast is operated according to strict guidelines laid down by the National Radiological Protection Board.

But local councils have little power to control where masts are erected as they do not require formal planning permission.

Bernard Stone, of Manchester City Council, said: "What we have agreed to do is to have an independent report into the safety of the mast on St Margaret's."

Base station transmitter masts mark the centre of each mobile phone network. They allow radio signals to be passed seemlessly between one mobile phone handset and another without interuption.

Industry rebuts fears

Tom Wills-Sandford says the masts are safe

Tom Wills-Sandford, of the Federation of the Electronics Industry, said research into the impact of radio waves had been going on for more than 50 years.

He said: "There is no scientific evidence that masts on or near schools can affect health."

Mr Wills-Sandford said the mobile phone industry was dedicated to ensuring that their products were safe.

Tom Wills-Sandford: "No evidence of health risks"

But he said masts had to be built in the community, because they had to be situated where mobile phone traffic was at its greatest.

"There will be more masts because mobile phones are growing in popularity," he said.