Trains are currently unable to run to and from Hastings Railway Station due to a broken down train.
According to Southern Rail, services will start and terminate at Bexhill for services to/from Eastbourne, Brighton and London Victoria where possible.
Disruption is expected to continue until 10am.
On its website, Southern wrote: "A broken down train near Hastings is causing delays and alterations to trains between Hastings and Tunbridge Wells / Eastbourne.
"A train has broken down on the London bound line at St Leonards Warrior Square. Response staff are on the way to investigate the problem with the train but until the train has been moved the line is blocked.
"Your overall journey time will be extended by up to 60 minutes. Where possible, please delay your journey until later."
Rail replacement buses have been arranged to run between; Bexhill, St Leonards Warrior Square, Hastings and Ore.