Some trains in and out of Portsmouth cancelled or altered amid track defect at Portsmouth Harbour

At least two services to Brighton and London Waterloo have been scrapped this morning because of the issue, which was flagged up by National Rail at 4.40am.

The firm said fewer trains are able to run to and from Portsmouth Harbour because platform three of the station is currently blocked.

National Rail has urged rail users to allow extra time for their journeys today and has said disruption is expected until the end of the day.

Service plan has been updated

National Rail said services which operate between Brighton and Portsmouth Harbour will begin and terminate at Fratton.

Meanwhile London Victoria to Portsmouth Harbour services will run as scheduled, as will trains travelling between Littlehampton and Portsmouth and Southsea.

In light of the fault, Southern Rail tickets will be accepted on South Western Railway services between Portsmouth Harbour and London, as well as London Underground services between London Waterloo and London Victoria.