Sydney commuters face a long trip into the city this morning, with delays on several major train lines due to a signal failure.

CityRail has advised of major delays on the Inner West, Bankstown and South lines after a signal failure at Carramar earlier this morning.

A RailCorp spokesman said the signal was repaired by about 8.15am, but delays were expected to continue into peak hour.

Trains have been suspended between Sefton and Carramar in both directions and buses will run between Liverpool and Lidcombe in both directions.

A shuttle train service is running between Macarthur and Liverpool.

CityRail said commuters could use the Airport and East Hills line as an alternative and normal rail tickets will be recognised at those stations.