Two men have been arrested as part of an investigation into the theft of £2m of rail track from across the Midlands and South Yorkshire.
British Transport Police said the men, aged 50 and 54, were arrested earlier on suspicion of conspiracy to steal railway track.
It comes after two raids on properties in the Bessecarr area of Doncaster.
Officers said the track was possibly being smelted down and sold on through scrap metal dealers.
Ten people, who were arrested in a series of raids in November, remain on police bail, British Transport Police said.
A spokesperson for the force said it was unusual for track to be stolen and much of the investigation was dedicated to locating what those involved were doing with it.
To date, Operation Ultimatum - which was set up in 2016 to tackle thefts across South Yorkshire, Lincolnshire, Nottinghamshire and the West Midlands - has involved more than 100 officers.