A major signalling failure at London Waterloo has caused severe disruption throughout the morning, with 14 platforms out of use at the station.
South Western Railway (SWR) has urged passengers not to travel on its services “until further notice” as there were cancellations on all routes, with problems expected to continue until at least 16:00 BST.
Passengers have been told they cannot claim money from SWR for taxis but can use their tickets on some other rail or bus services.
The rail operator said engineers were trying to restore the use of the platforms, but “very few trains able to move in and out” and many other train services across the network were “severely disrupted”.
Network Rail said: “While we are hoping to restore some services later in the day, these are still likely to be subject to delays and alterations.
“Customers should please check back for updates. We are very sorry for the disruption to journeys this morning.”
The incident was reported at around 05:30, according to National Rail.
Passengers can use their rail tickets on specified routes with London Buses, Falcon Buses, Stagecoach South, and Morebus operators as well as certain train journeys on the Tube, CrossCountry, Southern and Great Western Railway.
SWR was the first operator brought into public ownership by the Labour government in May, with a second train company, c2c, nationalised by Labour on Sunday.
Operator c2c runs services between London Fenchurch Street and south Essex.
