The British Railways Board (BRB) has issued a private list of the first 600 items it wants to sell from a portfolio of 1,400 sites across the country.
The BRB believes the portfolio is worth pounds 174m, but the final receipts could be much higher at auction. Campaigners are angry that only 200 of the 1,400 properties have been set aside for possible transport use and claim that many of the others make up crucial parts of local transport plans. The list includes station car parks, goods yards, former stations and signal boxes, playing fields, viaducts, disused railway lines axed by Dr Beeching, and even a row of shops.
Campaigners plan to write to John Prescott, the Deputy Prime Minister, saying that selling off sites such as station car parks will undermine plans to integrate trains with other modes of transport.
Stephen Joseph, director of the pressure group Transport 2000, described the sell-off as "daft". He said: "The Government wants to promote integrated transport with more people driving and cycling to train stations. But by the time councils start work on this they will find that all of the land has been flogged off for office blocks."
The Government called a halt to such sales last year pending a review after pressure groups warned that important sites that could be converted back to transport use were being lost.
David Begg, the recently-appointed head of the Government's Commission on Integrated Transport, was briefed about the plan at a conference on Friday. The sale will put him in a difficult position because he will be reluctant to criticise ministers.
David Redgewell of Transport 2000's south-west group, said plans to sell off land at Wapping Wharf in Bristol, Saltford station near Bath, and Henbury station, Gloucestershire, conflicted with local plans to build new public transport schemes.
"This is the great railway land sell-off. Who would have thought that a Labour government would be selling off all of the railway's assets? So much for our Government wanting to protect the railway infrastructure."
The list of 600 sites has been sent to councils, transport operators and pressure groups. They now have 60 days to come up with plans to bring the other sites back into use before the list is released to the open market. A series of auctions will be held around the country in the spring, at which property developers will be able to bid for the land.
A spokesman for the British Railways Board, which is mandated to dispose of unwanted land, said: "We are charged with getting best value for the properties because they are government properties."
But he said transport groups could appeal to Mr Prescott if they were outbid on the grounds that there were wider policy reasons why the land should be retained for transport uses.
The list of 1,400 sites is highly eclectic. It includes a row of shops on Finchley Road in north London, and the former British Rail Staff Association building at Carnforth, Lancashire - the station immortalised by the Second World War film drama Brief Encounter.Reuse content