The first of Sydney’s new intercity trains have been unveiled, but the government has no set date to operate the multi-billion dollar fleet as a union dispute drags on.

NSW Transport Minister Andrew Constance said on Tuesday the trains would begin arriving in sets of 10 each month from mid-2020. The fleet was originally due to be delivered from South Korea in early 2019.

State Transport Minister Andrew Constance aboard one of Sydney's new intercity trains.CREDIT:NICK MOIR

Mr Constance blamed union disputes and the COVID-19 pandemic for delaying the trains, which will operate across the Central Coast, South Coast, Newcastle and the Blue Mountains.

"There was, last year, a lot of effort going into the design of the train which did put it back a couple of months," Mr Constance said as he unveiled the first of the 55 trains in Hurstville.

"The COVID situation could also add to delays."

The $2.4 billion trains have been the subject of an ongoing war between the government and the Rail, Tram and Bus Union, with the modern fleet originally designed to operate without a train guard.

Transport Minister Andrew Constance says more of the intercity fleet will begin arriving in NSW by mid-2020.CREDIT:NICK MOIR

While the government has since conceded to allow a driver and a guard on each train, the union has no guarantees its members will staff the new fleet.

"It hasn’t changed, in fact it’s got worse," union secretary Alex Claasens said of the industrial negotiations.

"There’s a fair bit of work that needs to be done yet. We’ll get to a point where we just refuse to work it."

He said union delegates had been given two opportunities to inspect the trains, which are being tested across the state’s network.

Mr Claasens said the trains were not yet safe to be operating, given guards could not physically peer out of the trains to check platforms were clear.

Transport minister Andrew Constance shows off the new Intercity train fleet on Tuesday at Hurstville. CREDIT:NICK MOIR

But Mr Constance said NSW was one of the last jurisdictions in the world where rail staff leant out of the train to check the platform, and modern camera technology meant the method wasn’t needed.