A commuter town the size of Burgess Hill could be built in the Sussex countryside to meet the county's need for new homes.

Councillors in Brighton and Hove and East Sussex have joined forces in an effort to find a site for 22,500 houses that have to be built by 2021 to meet government targets.

There is no firm location for the town but countryside between Lewes and Uckfield is the most likely candidate, particularly if the railway line between the two, controversially closed 30 years ago, is reopened.

Planners said there was room for a major new development and the land could be bought under the new Planning and Compulsory Purchase Bill, expected to be given Royal Assent this summer.

Until now, the hunt for building land in Sussex has focused on filling in gaps within existing towns or building suburbs on the outskirts.

Under that policy, Bexhill, Hastings, Haywards Heath and Burgess Hill are in line for major expansion.

But planners have accepted the rate of growth in the county - where four out of five new homes are bought by people moving into the area - requires drastic action.

About 2,300 homes have been built in East Sussex every year since 1991 and obvious locations are running out.

By 2021, at least 11,250 homes will have to be built on green fields - the number of homes in Burgess Hill.

The planners have ruled out huge swathes of the county because they are subject to environmental protection, prone to flooding or unsuitable for building.

Their ideas, published in a report by the Joint Strategic Planning Advisory Committee, will be given a first airing at a meeting on Tuesday.

The two councils have already accepted the proposals will be unpopular but are confident of government support.

The report has been put together by Jenny Rowlands, director of environment at Brighton and Hove City Council, and Bob Wilkins, director of transport and environment at East Sussex County Council.

It reads: "The scale of development opportunities appears so limited that it is becoming increasingly evident we are very unlikely to be able to meet the requirements placed on us through development within, and extensions to, the towns in the plan area.

"We are therefore on the threshold of having to consider seriously the idea of developing one or more new settlementsif we are to accommodate anything like the scale of housing expected.

"This would constitute a major shift in the settlement pattern and would undoubtedly prove very controversial.

"It is too early to give any advice on potential locations for any new settlement."

The report states Brighton and Hove and the Eastbourne area have little scope for more housing because what land is available has already been earmarked.

Hastings and Bexhill have room for peripheral growth and have been identified as suitable for a substantial amount of housing.

Peacehaven, Newhaven and Seaford have been identified as having limited scope.

Uckfield and Hailsham have some development potential, although Uckfield has problems with flooding.

Lewes, Crowborough, Heathfield, Battle and Rye have no development potential.

Lewes MP Norman Baker MP, who is the Lib Dem's secretary of state for the environment, said: "I appreciate the county council has a need to build new housing and it has to go somewhere.

"The key questions would be where it is, how big it is and if it meets with public approval."

Mandy Park, clerk to the parish council in Isfield, which is midway between Lewes and Uckfield on the old railway line, said any development would be fraught with difficulty.

She said: "The railway line between Lewes and Uckfield is a flood plain.

"No one ever wants it on their doorstep but I can see all number of problems."