Coming on the back of health workers stopping work for a few hours last week over a 5.5 per cent raise, the Australian Paramedics Association (NSW) launched action on Monday to continue until Friday.

The union has placed a ban "staff movements", meaning paramedics will refuse to split from crewmates or travel from their designated station to fill roster gaps elsewhere.

The union says staff movements are routinely used to reallocate crews at the last minute when the service is short-staffed.

"Refusing staff movements means refusing to abandon your community to help the service cover up for shortfalls somewhere else", APA NSW President Chris Kastelan said.

The union wants 1500 more paramedics, a "genuine pay increase" and specialist paramedic programs to improve quality of care across the state.

"It's completely unacceptable that we're relying on a last-minute reshuffle of scant resources to get a single ambulance to our communities," Mr Kastelan said.

Under the state's wages cap, public sector pay increases are capped at 2.5 per cent.

The extended action comes as ambulance resourcing hit a critical low in metropolitan Sydney.

On Monday afternoon, 104 Sydney patients were waiting for a response when just one transport ambulance was available, the APA NSW said.

This meant Sydney was designated a Status 3, the highest emergency designation.

"We want enough crews on the road to cover the rosters. This shouldn't be a radical proposal."

Australian Associated Press