Thameslink rail disruption 'could last to Friday'
Disruption to train services between Bedfordshire, Hertfordshire and London could last until Friday, Network Rail has said.
Thameslink trains are suffering delays due to signalling problems resulting from damage to overhead wires at Luton on Tuesday.
The operator was still running a "limited service" on Thursday.
Network Rail said it expects disruption "until the end of service, but it may yet continue tomorrow".
Trains were disrupted after a signalling wire came into contact with overhead electric lines, it said.
Robert McIntosh, from Network Rail, said: "What we do know is one of our signalling cables did come away.
"A signalling system that normally carries 24 volts had a sudden injection of 25,000 volts. It has caused quite extensive damage, which is why it's taking us so long to put this right."
Thameslink is running a limited service across the network, with services cancelled, revised or delayed by up to 90 minutes.
It is offering bus replacement services to link up with other lines where passengers can use tickets.
Passenger services director Stuart Cheshire said: "Work carried out by Network Rail overnight has allowed us to run some more trains today between Bedford and St Pancras but the service is still severely reduced, meaning very difficult journeys for our passengers for the third day running and for this we sincerely apologise."