Warrants were executed at 12 addresses including houses and scrap metal dealers across South Yorkshire.
Ten people were arrested and are currently being held in custody where they will be interviewed by detectives.
Three of the arrested men ran scrap metal dealers in the county.
A number of vehicles were seized and stolen scrap metal and large amounts of cash was discovered at two of the premises searched.
More than 100 officers from across British Transport Police (BTP) were involved in the operation including specialist officers from the force’s high tech crime unit. Cash search dogs were also used as part of the operation.
Detective Chief Inspector Glen Alderson, from BTP, said: “The arrests made this morning as part of Operation Ultimatum, are the result of a six month investigation into the theft of £2 million of rail track by an organised crime group from 44 line side locations and depots in South Yorkshire, Lincolnshire, Nottinghamshire and Birmingham.
“Our investigations are ongoing and I would ask anyone with any information to contact us on 0800 405040 or text 61016 in strict confidence.”