A fault on a train at Clapham Junction is causing disruption to Southern services between East Croydon and London Victoria this afternoon.
Southern says the incident is affecting services between Balham and London Victoria, with some lines currently blocked.
The operator initially reported on its website that there had been a fire on a train, but later changed its description of the incident to a train fault.
British Transport Police told V2 Radio at 13:21 that officers believe there was a fault with the train and possibly some smoke, but no fire.
Trains travelling to and from London Victoria may be delayed by at least 15 minutes, cancelled or revised, with disruption currently expected to continue until around 15:00 today, Thursday 20 August.
Some services are being diverted onto an alternative line and are currently unable to call at Battersea Park or Wandsworth Common.
Passengers using those stations are being advised to use London buses to or from Clapham Junction or London Victoria to connect with rail services.
Southern says passengers may need to use alternative routes and should allow at least 20 minutes extra for their journeys.
Tickets are being accepted at no additional cost on alternative Southern services between East Croydon and London Victoria, as well as on London buses between Balham and Victoria.
Southern's disruption information was last updated at 12:33 this afternoon, with the disruption expected to continue until 15:00.
This is a breaking story and will be updated as further official information becomes available.
Listen to V2 Radio travel news for the latest updates.
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