Sydney trains cancelled due to industrial action, with warning of ‘very difficult day’ ahead

All Sydney trains have been cancelled due to industrial action, leaving thousands unable to make their Monday morning commute.

Workers have been warned to brace for a "very difficult" day by the Sydney Trains chief executive, Matt Longland.

"We're urging customers to obviously avoid travel today or to use the transport journey planner to look for alternative options, such as buses, ferries and light rail if possible," Longland told the radio station 2GB.

Services will be disrupted across the city, including routes connecting Sydney to the Blue Mountains, the south coast and Newcastle. Buses will replace some services but commuters are being told to allow for extra travel time.

Extra buses will be added to the network today, the Transport for New South Wales secretary, Rob Sharp, confirmed early on Monday morning.

"We are doing everything possible to minimise the impact to commuters and sincerely apologise to everyone inconvenienced by this industrial action," Sharp said.

Services were cancelled about midnight last night after negotiations between the Rail, Tram and Bus Union and Transport for NSW broke down, following dozens of meetings.