London mayor Boris Johnson's plans to construct a new airport off the coast of Kent and Essex in the Thames Estuary have been criticised by a new report drawn up by Medway Council.

In its Thames Estuary Airport - Feasibility Review document, the council has identified a number of key concerns regarding the scheme that cast doubts over the viability of the scheme. According to the council, the proposed Thames Estuary airport would be located 60 miles (96.6km) from the capital - equivalent to moving Bristol International Airport to the other side of Cardiff, or relocating Manchester Airport to Leeds.

Other concerns include the proximity of the planned airport to Thamesport, a facility used for the unloading of Liquid Natural Gas, and the increased risk of birds striking aircraft taking off or landing in the Estuary. A new railway hub may also be required to facilitate the necessary transport links to the airport, which could add £40bn to the total cost of the project.

Council leader Rodney Chambers said: "This report to Cabinet shows exactly what we already knew - that the Mayor of London's plans for an estuary airport are completely pie in the sky. "His feasibility study has not taken into account so many things such as the distance it would be from London and whether passengers or airlines would actually want this, it has ignored the fact that there is a port importing a huge quantity of Liquid Natural Gas everyday and has made only a very arbitrary study of the transport links needed."