SYDNEY, AAP – Sydney train commuters have been warned to expect delays to the network on Tuesday morning after an overnight strike.

The Sydney Trains-operated network was disrupted from 8pm on Monday to 4am on Tuesday as Rail, Tram, and Bus Union members took industrial action.

Buses replaced train services on all lines between 8pm and 4am, but Sydney commuters have been encouraged to avoid travelling on Tuesday morning.

The union is at loggerheads with Transport for NSW as they negotiate a new enterprise agreement covering more than 10,000 staff.

The strike comes after industrial action last Tuesday when RTBU members refused to drive foreign-built trains used on about 75 per cent of services.

Transport for NSW said workers had been offered new enterprise agreements, including a 2.5 per cent pay rise in the first year.

The union wants a 3.5 per cent wage rise.