British Transport Police officers are handing out water to passengers who have been stuck on a delayed train from Haywards Heath since 7.20am this morning (April 30).
A passenger on the train said some delayed trains have been evacuated and said there is no air con on the train.
Jason Parker, @jdsp1974 tweeted: “@OliviaLerche @SouthernRailUK @midsussex_times train in front hit a power line apparently. Police on train offering water. Some trains evacd.”
He added: “@OliviaLerche @SouthernRailUK @midsussex_times odd that you get updates from BTP but not Southern or the driver/conductor.”
He said the train was sitting near Balham.
A spokesman for Southern Rail said: “A major power supply problem between Clapham and Wandsworth Common has disrupted Southern train services into London Victoria this morning. Engineers are on site and we aim to resume services as quickly as possible.
“Services into and out of Victoria are currently suspended. Southern tickets are valid on all other routes into London and Southern passengers are advised to avoid travelling through Clapham Junction, which is very busy.
“There is no estimated time yet for the resumption of services.”