THE Appeal Court dealt a blow last night to campaigners battling to stop a phone mast being erected near three schools - and cleared the way for thousands more.

Although the plans for a 25-metre high mast in North Yorkshire were opposed by local councillors, parents and teachers, a judge sided with a legal challenge brought by three mobile phone companies.

The landmark decision is expected to have far-reaching consequences.

More than 12,000 other phone mast planning applications are said to be hanging on the result - including hundreds in the North-East and North Yorkshire.

Campaigners said the decision gave mobile phone companies the go-ahead to site mobile phone masts on or near schools throughout the UK. They fear the radio waves emitted by such masts are linked to ill-health - a claim denied by phone companies.

Parents from St Robert's RC Primary, Woodfields Primary and Granby High School, in Harrogate, took their fight to stop a mast being built on nearby Claro Road to the Appeal Court yesterday.

Harrogate Borough Council originally refused the mast planning permission. But in June, the companies behind the development - T-Mobile, Orange and Hutchison 3G - took the case to the High Court.

A judge ruled that the planned mast met safety guidelines and yesterday Lord Justice Laws again ruled in favour of the companies. He said: "It remains central Government's responsibility to decide what measures are necessary to protect public health."

Parents who set up the campaign group Campus - Campaign Against Masts Put Up Near Schools - have argued that masts should not be built until the effects on health have been fully investigated.

Last night, campaign group member Juliana Hodgson, who has two children at St Robert's, said: "We are very disappointed by what has happened.

"This decision has an effect on children throughout the country in that health can't be used as a consideration in planning applications for a mast."

She added: "We wanted them to use the precautionary principle and not site masts near schools until such time that there is research to prove they are safe."

Harrogate MP Phil Willis also voiced his consternation at the decision.

Mr Willis, who is chairman of the all-party mobile communications group, said: "The decision of the Appeal Court to uphold the mobile operators' plans to erect a mast near three schools is a body blow to concerned parents throughout the country.

"The effect of this decision is to give mobile phone operators freedom to site masts on or near school playing fields throughout the United Kingdom.

"This judgement is so fundamental, I have today written to the Secretary of State John Prescott to urge him to take this case to the House of Lords."

A spokesman for the Diocese of Leeds, on behalf of St Robert's School, said: "We are not surprised by the judgement in the High Court.

"However the parents at the school feel badly let down."

A spokesman for T-Mobile said: "We are delighted with the outcome.

"This confirms that the existing framework for securing planning permission - maintaining, upgrading or installing mobile phone masts - is what should be followed."