Rail passengers travelling between Gatwick and East Croydon faced cancellations and delays this morning (Wednesday September 26).
Southern said that urgent repairs were being carried out on the track between these stations.
Earlier this morning it was advised that a track defect was found in the Coulsdon South area.
Network Rail operatives were sent to carry out repairs, with the work estimated to take around 90 minutes.
The engineers arrived on site at 8.30am.
This was a temporary fix, with a permanent fix to be implemented overnight.
Non stopping services that run on the fast lines between Gatwick Airport and East Croydon were subject to delays, cancellations and alterations.
A reduced Gatwick Express service was in operation.
Some Southern Southampton Central and Bognor Regis services terminated and restartedat Three Bridges.
This also affected Great Western Railway services which were unable to run between Redhill and Gatwick Airport.