A points problem is causing disruption between London Bridge and Streatham Common this afternoon.
National Rail said trains may be delayed by up to 15 minutes, or revised. The disruption is expected to last until 1.30pm.
"We have received information regarding a points failure at Streatham. This is affecting services running towards Streatham Common via Tulse Hill," National Rail said.
"Services running between London Bridge and West Croydon will be diverted via Crystal Palace.
"Tickets are currently being accepted on London TfL buses via any reasonable route."