Engineering work by Network Rail has overrun leading to delays on Southern services this morning.
While work was carried out overnight on the line between Brighton and Haywards Heath, engineers suffered delays and Southern have warned this may affect services.
Southern said their services are subject to delays, alterations and short notice cancellations this morning.
They advise that customers "listen carefully to all station and onboard train announcments for further details".
In statement on their website they said: "Southern together with Network Rail is working as fast as possible to restore services back to normal."