by political editor Paul Francis

Boris Johnson has repeatedly snubbed requests to discuss his controversial plans for an island airport with council leaders in Kent, according to letters obtained by the KM Group.

Correspondence between Cllr Paul Carter, the leader of Kent County Council, and the Mayor of London reveal how the two have squared up over the scheme, near Sheerness, and how Mr Johnson fobbed off a succession of pleas to discuss it despite its potentially huge impact for Kent.

In a series of letters, it also emerges that Cllr Carter urged the Mayor not to refer to the airport plan in the run-up to the county council election, fearing it could damage the Conservative Party's prospects.

He urged Mr Johnson to refrain from talking about the plan until after the June local election in Kent last year, saying: "I believe such plans coming from a senior Conservative figure could damage our cause locally," - a fear that proved unfounded.

Frustrated by the Mayor's apparent reluctance to agree to a meeting, he eventually pressed the shadow transport secretary Theresa Villiers to broker a meeting. Even that failed.

The correspondence began soon after Mr Johnson was elected as Mayor of London in May 2008.

Days later, Cllr Carter wrote suggesting the pair meet because there were a "number of big issues that need to be chewed over" and outlined his opposition to Boris Island. In it, he said: "The need for a fourth London airport is, I'm afraid, a subject we will have to disagree on".

The Mayor responded by offering a meeting with Ian Clement, one of his deputy mayors.

Two months later, Cllr Carter set out his opposition to the island airport plan, sending the Mayor a dossier of papers and reports which he said amounted "to a very strong argument against a Thames Estuary airport".

But it appears the Mayor did not respond and in January last year, Cllr Carter was prompted to write after Mr Johnson came to Kent for a fact-finding boat trip to visit the site and confirmed his support for the estuary airport.

In his letter, Cllr Carter wrote: "I am sure Sir Simon Milton [deputy mayor] may have told you that I was not desperately impressed by your boat trip last Friday which has seriously upset residents from the Medway Towns to Ramsgate."

The letter went on: "I again extend an invitation to you and your team to come and visit us at the chalk face."

The Mayor replied but again appeared unwilling to cross into Kent, writing: "As you say, I think we are going to have to disagree about the merits of an airport in the Thames Estuary" but adding in a hand-written note: "I am sure we are in basic agreement...Manston could play a vital role in the eventual solution."

Frustrated at the Mayor's apparent reluctance to meet, Cllr Carter finally wrote to shadow transport secretary Theresa Villiers, saying: "I have been trying with little success to get Boris Johnson to Manston.

"If we could try to arrange a joint meeting, it would be really beneficial for all."

A month later, after the Mayor signalled in media interviews he was prepared to visit Manston, Cllr Carter wrote again suggesting a meeting.

Eventually in April last year, the Mayor told Ms Villiers he would meet Cllr Carter - but only after a meeting with his deputy mayor Mr Clement had taken place.

But to date, no such visit or meeting has taken place and it appears none are planned.