SEVENTY local authorities have come out in favour of the Cliffe airport option to solve Britain's airport needs. And that has caused a major row with Medway and Kent councils who are against plans.

SASIG the Strategic Aviation Special Interest Group says Cliffe is a once in a lifetime opportunity and a bold approach to solving the problems of airport expansion. Both Medway and Kent councils have resigned from it.

Rodney Chambers, leader of Medway, said: "We have withdrawn from SASIG because the view being expressed was not in the best interests of the community we represent."

Mott MacDonald, which built Hong Kong's new airport, examined the Cliffe plans for Kent. They found that the proposed airport would cost £16 billion to build, £3 billion more than the Government estimate, and would involve raising marshland by 45ft a massive undertaking which would not be ready until 2018.

Kent leader Sandy Bruce-Lockhart said: "SASIG was set up to defend Heathrow against expansion."

Meanwhile a High Court judge has reserved judgement on whether or not Gatwick should be among the Transport Secretary's proposals.

Firm decisions on UK airport expansion will be made next year by Transport Secretary Alistair Darling. His barrister, Timothy Corner QC, told the High Court on Friday the decision to exclude Gatwick was not legally open to challenge.

In 1979 agreement was reached between the British Airports Authority and West Sussex County Council which prevented a second runway for 40 years.

It could only be overturned by legislation, which was not open to judicial review. Developing Cliffe would cost more than 1,100 residences and around 5,000 acres of agricultural land.

SASIG's report today said that local opposition should not be a reason for the Government to avoid taking "difficult decisions".

The group claims mitigation measures for bird life by flooding the Wantsum channel would be less than a quarter of the cost of compulsorily buying 15,000 homes for a new Heathrow runway.