Ambulances from the ACT Ambulance Service queue up outside Canberra Hospital.

Ambulances from the ACT Ambulance Service queue up outside Canberra Hospital. Photo: Christopher Knaus

The ambulance union has warned changes to the ACT's patient transport service could slow ambulance emergency response times and see workers lose hundreds of dollars from their pay.

The government is seeking to change the operating hours of the Patient Transport Vehicle, a unit funded by ACT Health which speeds up the discharge of patients from Canberra and Calvary hospitals. The proposal would make the vehicle available from 9am to 6pm on weekdays, rather than the current hours of 11am to 7.30pm.

The changes have angered the 10 ACT Ambulance Service support officers who rotate through the ACT Health vehicle and two other patient transport vans not subject to the changes.

The Transport Workers Union said the 10 officers could stand to lose $300 from their pay when they work from the ACT Health vehicle.

TWU official Ben Sweaney said the changes would also increase the burden on paramedics, who would now have to cover more of the patient transport work.

''What we're seeing is stations being closed, we're going below minimum crewing, because intensive care paramedics are picking up [patient transport] work because there's nobody there doing it,'' he said.

''It's delaying response times, so when people do call triple-zero for an emergency, the potential is there that the response will be delayed.''

Mr Sweaney said many of the officers were considering leaving the service, and industrial action had not been ruled out.

But the ACT Ambulance Service said no concerns had been raised with management. A spokesman said the service had written to members as part of its efforts to consult on the roster changes.

ACT Health said the vehicle's weekend operating hours would not change, staying at 9.30am to 6pm.

The dispute between the union and the government continues a series of heated exchanges over workplace issues since the recent ACT election.

In October, the Transport Workers Union attacked the government over the low morale of the service, which it says is due to mismanagement, intense work pressures and a failure to address a ''dysfunctional and toxic'' culture.

The union has also strongly criticised management over an error that saw ambulance officers forced to pay back tens of thousands of dollars in leave entitlements.

Allegations that some senior emergency services officials were inappropriately accessing a lucrative tax exemption were referred to the Australian Taxation Office earlier this year.