Commuters are facing travel chaos this morning after a trespasser was spotted on the line.
Rail passengers travelling between Norwood Junction and London Bridge and Crystal Palace and London Bridge face delays this morning because of a trespass incident.
Passengers have reported chaos at East Croydon because of delays and cancelled services.
Southern said crowd control measures had been put in because of overcrowding.
The trespasser is understood to be on the tracks at Honour Oak Park, and services run by Southern and First Capital Connect and the London Overground are affected.
Tickets are being accepted on London Underground, South eastern, South West Trains, First Capital Connect and bus services.
Passenger are warned to expect delays of up to 60 minutes and cancellations as there is no current estimate for when a normal service will resume.