More than 700 regional Victorian ambulances will be without maintenance workers as they take "unprecedented" strike action after a breakdown in contract negotiations.

About 23 fleet maintenance officers, responsible for servicing ambulances across regional Victoria, will walk off the job for 24 hours on Monday after long-running pay negotiations stalled.

Workers bargaining for 14 months accused Ambulance Victoria of failing to recognise their crucial role in keeping the emergency vehicles on the road and refusing reasonable pay increases amid cost-of-living pressures.

They said a workload which involves being on call at all hours was unsustainable.

The United Workers Union says the pay of ambulance mechanics lags their counterparts in other emergency services.

Ambulance stations in Ballarat, Bendigo, Geelong, Hamilton, Horsham, Morwell, Shepparton and Wangaratta will be affected by the strike.

"Ambulance Victoria doesn't seem to get how important fleet workers are in providing much-needed ambulance services in regional Victoria," the union's national ambulance coordinator Fiona Scalon said.

"The action is a historic first - there is no record of fleet officers being pushed to take this kind of action previously."

Ambulance fleet maintenance officer Lyle said: "We're not accepting scraps once everyone else has had their fill".

Backup plans have been put in place to ensure the action won't impact on the public's safety.