Protesters stand a good chance of taking the Government to court to block new mobile phone masts, according to a pressure group.

A swathe of recent High Court judgements have ruled against the Government and mobile phone companies if planning inspectors had failed to consider health when making a decision about whether to allow a mast.

Previously, many local authorities claimed that objecting to the masts on health grounds was irrelevant because the masts fall within guidelines set by the International Commission on Non-Ionizing Radiation Protection (ICNIRP).

Lisa Oldham, from the group Mast Sanity, said: "Local councils have been bullied by the Government into not taking health as a planning consideration. But if 300 people were to complain about health not being taken into consideration then, in theory, they should win."

The recent rulings also open the door for residents to contest previous decisions which have used the ICNIRP guidelines as an excuse not to look at health.

Last week, Mr Justice Richards revoked the permission of Hutchinson 3G to erect a 40-foot mast 22 yards from the front door of a pregnant 27-year-old woman in Hampshire.

"The planning inspectors are getting it wrong. A lot of councils were refusing masts and the inspectors [on behalf of the Government] were overruling them and saying the masts conformed to ICNIRP. All of those decisions are wrong," said Mrs Oldham.

In planning guidance to local authorities, the Government said health can be a material concern. But in the next paragraph it said: "However, it is the Government's firm view that the planning system is not the place for determining health safeguards."

Mrs Oldham added that many councils were so worried about wasting money on appeals made by phone companies against planning refusals that they simply gave in.

"They feel that the threat of being taken to court, although more expensive, is less likely than that of going to appeal and losing," she said.

Despite the threat of legal action, a spokesman for Barnet Council said it had not changed its policy on smaller masts. "Phone masts under 15 metres traditionally can only be opposed on appearance and siting grounds," he said.

Last month, a study by Dutch scientists claimed third generation mobile phone emissions did affect well-being, causing headaches and nausea. Mobile phone companies have claimed that the research is not credible until it has been independently corroborated.