The dispute, involving multiple unions, has dragged on for more than eight months, with paramedics seeking between a 25 and 45 per cent pay increase which the government says it can't afford.
On Friday, a planned action by the Health Services Union for around 1900 of its members not to renew their registration came into effect.
Taking into account a four-week grace period, the registrations would lapse at midnight on New Year's Eve, meaning workers would be able to do little more than drive ambulances and give basic first aid from January 1, the HSU says.
Health Services Union NSW secretary Gerard Hayes wants a jump in pay for paramedics. (Dean Lewins/AAP PHOTOS)
Premier Chris Minns said as a result those paramedics could not be rostered on to work, holding massive implications for the triple-zero network.
"If someone was picked up who had a coronary episode or a heart attack, and was in the back of the ambulance, the paramedic wouldn't be able to perform life-saving interventions to save that life because they wouldn't be registered," he said.
"We need to make sure that this industrial action doesn't spill into having unintended consequences where people who are very sick or could potentially die can't have access to a paramedic or an ambulance to get to hospital."
HSU NSW secretary Gerard Hayes, said responsibility for any disruptions to services lay squarely with the premier.
"The premier is correct to point to serious disruption starting from New Year's Day," Mr Hayes said.
"If he kept his promise to recognise the life-saving skills and responsibilities of paramedics with professional pay we could avoid this."
The HSU is seeking a 20 per cent pay rise to bring rates in line with those in Queensland, on top of the existing base public sector pay increase, currently four per cent.
Mr Gerard said the union is trying to stem the flow of workers leaving NSW for better pay elsewhere to prevent the collapse of the state's workforce.
Health Minister Ryan park said an offer to bring in third-party arbitration was rejected by the union on Friday morning.
"We have agreed with the Health Services Union that we will continue to talk and negotiate next week," he said.
"We do agree that our paramedics need to be paid more."
NSW Health Minister Ryan Park says the government agrees paramedics should be paid more. (Bianca De Marchi/AAP PHOTOS)
Also on Friday, Paramedics from the smaller Australian Paramedics Association, launched industrial action, defying orders made by the state's Industrial Relations Commission.
APA members said they would attend emergency "lights and sirens" jobs but limit other responses for 12 hours starting from 7am.
The commission late on Thursday ruled the action would not be protected, with the campaign also condemned by the HSU.
"This strike symbolises our unyielding quest for justice," APA president Brett Simpson said in a statement.
