Trains services through Gatwick Airport, Brighton, Hove, and Littlehampton are being disrupted this afternoon (June 29).
Services via Preston Park have been affected due to a signalling fault at the station this afternoon (June 29).
Southern Rail said: “Please postpone your journey or leave a significant amount of extra time if you are using trains to and from Brighton, Hove and Littlehampton.
“These services had already been delayed due to speed restrictions (related to hot weather) and a signalling problem at Clapham Junction, and are now further disrupted by this incident.”
Keep updated on the Southern Rail website and by following @SouthernRailUK on Twitter.