Southern Rail posted on its website the following statement. It said: "Earlier this morning, Network Rail advised of overrunning engineering works at Shoreham-by-Sea. This meant trains were unable to run between Hove and Littlehampton.
"Most planned engineering work by Network Rail happens overnight, at weekends and on bank holidays, as this minimises disruption to passengers whilst also keeping engineers safe. Sometimes bad weather, machinery failure or unexpected complications can cause works to overrun. When an issue does occur, we work closely with Network Rail to quickly assess the situation and to complete remaining repair works, so train services can be restored as quickly as possible.
"Overrunning engineering works between Littlehampton and Hove have now been completed and services are beginning to return to normal between Littlehampton / Barnham and Brighton. However, trains may still be cancelled, delayed by up to 30 minutes or diverted via Horsham whilst service recovers.
"Disruption is expected to continue until 10am."
Tickets will be accepted on some buses and by other railway operators.