Trains from London Waterloo to Dorking and Hampton Court via Wimbledon have been cancelled this afternoon.
Signalling problems at Wimbledon and Earlsfield have caused problems on the lines, leaving passengers facing delays all afternoon.
South West Trains – Network Rail Alliance has apologised for the inconvenience to passengers.
A spokesperson said: "Services travelling between Wimbledon and London are facing delays this afternoon following a signalling problem between Wimbledon and Earlsfield.
"As a result, both the London Waterloo to Dorking trains in both directions and the London Waterloo to Hampton Court trains in both directions will be cancelled until further notice.”
The spokesperson said Southern Trains and London buses will be accepting South West Trains customers with tickets on their trains via any reasonable route.
Passengers are advised to check National Rail Enquiries before starting their journey.
The spokesperson added: "We're sorry for any inconvenience caused to passengers."