A broken down train at Blackfriars station earlier today is continuing to wreak havoc on the Thameslink network, with delays expected until later this afternoon.
There is disruption on routes between Brighton/Sutton and Bedford and it is expected to continue until 1pm.
Technicians have repaired the fault on the train to enable it to move and the line has reopened, however National Rail warned services may be delayed or subject to alteration due to congestion.
"Due to the frequency of our services small delays can quickly build up," the rail operator said.
"The control team are working as quickly as possible to restore normal service this can result in some services being revised."
National Rail advised passengers that they may be able to reach their destination more quickly by using another operator or by travelling to an alternative nearby station.