British Transport Police detectives investigating the theft believe the gang made several trips over four days and used a fork-lift crane to escape with the disused track.
They are believed to have mounted the operation to steal the track between Thursday, June 17 and Tuesday, June 22.
Detective Sergeant Matt Davies, investigating officer, said: “We believe that they used a forged contract, which staff at the station took as legitimate, in order to lift and load up the wagon.
“The thieves were last seen entering the station at around 5am on Monday, June 21 and leaving three hours later with a wagon laden with rail.
“They returned later that day at 12.15pm and left approximately an hour later with the same wagon, again loaded with stolen rail.”
Det Sgt Davies said 357 20ft sections of metal weighing around 119 tonnes and 30 10ft sections weighing around five tonnes were taken.
The track was later traced to a scrapyard near Blackburn.
Neil Johnson, route infrastructure maintenance director for Network Rail, added: “This was redundant track which was awaiting collection by our scrap contractors.
“These thieves were clearly very organised and convincing. We are working closely with police to bring them to justice.”
“Security of all of our sites is of high importance and under constant review. This area already has CCTV which will be reviewed as part of the investigation.”
Anyone with any information is asked to contact BTP on 0800 405040 quoting incident number 213 of 22/06/10 or call CrimeStoppers anonymously on 0800 555111.