A fire near Wimbledon station is expected to cause huge delays until the end of service.
Thameslink took to Twitter to say that the "major disruption" is also being caused by signal failures at other stations on the network.
Currently Thameslink services are unable to run along the Sutton-Wimbledon route.
National Rail have adived people to use Southern services from London Victoria/London Bridge.
London Buses and Tramlink services are also available
Additionally there has also been a loss of power at Wimbledon station affecting platform 9 where Thameslink run its services towards Bedford via Sutton and Mitcham Junction.
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