Power cables worth £100,000 have been stolen from a railway line over Christmas.
Network Rail warned passengers to expect disruption between Chorley and Bolton and services to Preston to be affected on Sunday following the theft.
The firm said it would have to close the line so it could replace the cables and test the system.
Network Rail said it is working with the police to find the culprits.
Since 2022, Network Rail has been electrifying the line between Wigan and Bolton.
The stolen cable provided power to the overhead line equipment, which in turn powered electric trains across the tracks.
"I am very sorry to passengers who will be impacted by the rail closure," Christian Irwin, Network Rail's capital delivery director, said.
"We are working closely with the British Transport Police to provide additional security measures and to find and prosecute those accountable."