Southern Rail said a ‘trespass incident’ is causing disruption to trains between Lewes and Seaford.
Delays are expected until 5pm.
Southern said: “A trespass incident in the Seaford area is causing disruption to trains between Lewes and Seaford. Trains may be cancelled or delayed. Disruption is expected until 5pm.
“The power to the track has been switched off as a safety precaution, no trains are able to run at this time.
“Initial reports have been received of a trespasser in the Seaford area. Emergency services are en route to assist with this incident, and we will keep you updated with any updated information.”
There were also trespass incidents on the Seaford line last week on Wednesday (November 7) and Thursday (November 8).
At 3.50pm, Southern said: “The trespasser has been removed. Power to the lines will be restored shortly, at which point lines will be reopen for service.”