Commuters on South Western Railway have been told not to travel after engineering works overran.
No SWR trains are running between Surbiton and London Waterloo – the UK’s busiest railway station.
Woking, Surbiton, Raynes Park and Earlsfield stations have been closed and people advised not to travel.
The rail operator said services across its entire network may be cancelled, delayed or revised all day after work due to finish at 04:30 GMT was delayed.
The work is not due to finish until 08:30 but SWR warned that disruption “is expected until the end of the day”.
Normally-packed rush hour trains have been cancelled, leaving thousands of passengers stranded.
Rail passengers have taken to social media to complain about the latest disruption to hit SWR following a spate of problems involving signal and points failures.
A long-running dispute over the role of guards on trains has also crippled services because of strikes.
SWR operates services from London Waterloo to Berkshire, Surrey, Hampshire, Dorset, Devon, Somerset and Wiltshire.
A message to passengers said: “We have been informed of over-running Network Rail engineering works between London Waterloo and Surbiton.
“This means that trains cannot run between London Waterloo and Surbiton. Customers are advised not to travel.”
An SWR spokesman added: “Passengers are asked to delay the start of their journeys this morning as all lines from Surbiton into Waterloo are blocked due to over-running engineering works…
“We are sorry for the disruption and will update our website as soon as we have a clearer picture of when lines may reopen.”
Southern services between East Croydon and London Victoria have also been disrupted because of over-running engineering works.
The rail operator said services running to and from those stations may be cancelled or diverted via London Bridge. Disruption is expected until 09:00.
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