A cross-section of Lord Foster's plans for a new Thames Estuary airport

Exclusive by Alan McGuinness

Medway will know within the year if it is to be the proposed site for an international airport hub double the size of Heathrow.

Department of Transport officials have confirmed that an aviation policy would in place by next spring after both the Prime Minister and Chancellor this week signalled the start of serious debate about aviation capacity.

The official consultation, which will include an airport in the Thames Estuary, is not now expected to be announced until the summer.

Chancellor George Osborne said in his Budget speech yesterday, that the Transport Secretary would "set out government thinking later this summer".

Afterwards a Department for Transport spokesman said: "We have been working on a separate call for evidence on the options for maintaining the UK's status as an international hub for aviation.

"We remain committed to having a final policy in place by next spring at the latest.

The strategy was expected to be announced this month, and on Monday David Cameron confirmed for the first time an airport in north Kent was one of the options that would be considered.

In a speech on infrastructure Mr Cameron said he was "not blind to the need to increase airport capacity, particularly in the south east".

Mr Osborne said in the House of Commons yesterday: "I also believe this country must confront the lack of airport capacity in the South East of England.

"We cannot cut ourselves off from the fastest growing cities in the world."

Opponents of the idea, which include all political parties on Medway Council, the Towns' three Conservative MPs and wildlife groups, claim it would costs tens of billions of pounds and cause untold damage to wildlife.

Those in favour argue an airport would regenerate the area and bring in new jobs and investment.