Boris Johnson’s bill for promoting a Thames Estuary airport is 10 times more than the money spent by Medway Council fighting against the idea, we can reveal.

In the past three years the authority has paid more than £113,000 in an attempt to fight off a project which would change the face of Medway forever.

As well as its own funds, Medway Council has received money from Kent County Council (£13,500) and Greening the Gateway Kent and Medway (£12,000). Added together, the total spending comes to £138,544.38.

As we reported last month, Mr Johnson, the Mayor of London and a big supporter of the idea, has spent a staggering £1.4 million.

This figure could rise to £3 million by April – almost 25 times what the council has spent.

Campaign group Demand Regeneration in North Kent, which thinks opponents should reconsider, slammed the council’s spending.

Campaign director Clive Lawrence said: "It’s a complete and utterly fundamental waste of money for two reasons.

"One, that money could well have been put to a much better use, making a positive difference to Medway.

"The second reason is that they’re actually spending money to stop themselves effectively getting £100 million a year [through proposed changes to business rates]."

The council’s deputy leader Cllr Alan Jarrett (Con), who defended the sum as "excellent value for money", said: "This pales into insignificance compared to what the mayor has spent, and so far we’re winning."

The majority of the council’s cash (£126,507.31) has gone on paying consultants College Public Policy.

The council says the organisation has helped with its submission to the Airports Commission, secured an appearance before the Transport Select Committee earlier this year and assisted the council in making the case against an airport.

A host of other expenses are included, such as rail travel and office expenses (£1,561.51), designing an anti-airport website (£1,691) and £1,200 to attend aviation conferences.

A visit by the Airports Commission to Medway earlier this year cost £1,153.32.

An interim report by the commission due in December will include a shortlist of the best options for expanding the country’s aviation capacity.

A full report with final recommendations is due after the 2015 election.

In a speech earlier this month, the commission’s head, Sir Howard Davies, said new runways would be needed in the South East in the coming decades.

Grain and Cliffe have both been put forward as potential sites.