The NSW rail union has vowed to push ahead with planned industrial action this week in the face of the state government’s legal bid to block a second straight week of disruption on the transport network.

The Rail, Tram, and Bus Union is locked in a long-running stoush over a controversial Korean-made Intercity train fleet, arguing the NSW government has refused to sign a deal guaranteeing fixes to safety issues raised by drivers.

The government and the RTBU last week failed to broker an end to the dispute after the union knocked out 70 per cent of services on Friday. The union has foreshadowed similar action on Wednesday and Friday this week.

Premier Dominic Perrottet on Monday said the government would go to the Fair Work Commission to stop the RTBU, describing its conduct as “purely political”.

RTBU NSW secretary Alex Claassens said the government move was a step backwards in the dispute.

“At this stage Wednesday and Friday (are) definitely still on because there is no way in the world that we’re going to back off on any of our industrial action unless we get some sort of guarantee from the government that they are serious,” Mr Claassens told AAP.

The union had received notification that a hearing in the matter would go ahead at the FWC at 4.30pm on Monday, he said.

The government has signalled a willingness to spend $264 million to modify the fleet, but the union insists it needs written confirmation as previous offers were followed by backflips.

Transport Minister David Elliott has vowed to resign if he does not deliver on promises to the union and insists there are no safety concerns with the fleet.

Mr Perrottet on Monday reiterated the government’s pledge to fix the fleet.

“We’ve said that publicly, we’re making that a commitment,” he said.

Mr Claassens said the emergency hearing was a chance to get written proof of the government’s promise.

“We’ll be in front of a commissioner and then hopefully … we’ll be able to get some sort of guarantees from them on transcript,” he said.

Labor leader Chris Minns urged “round the clock” talks and said the government needed to give the union written assurance on fleet safety upgrades.

“It shows rail workers and the travelling public that the government is serious about ensuring that those Korean-built trains are safe to use and work on the NSW public transport system,” Mr Minns said.

Protected action on Monday saw trains sound their whistles, while other actions through the week are likely to include cleaners only working at their home depot and drivers not using the network to travel between stations.

– AAP