Ambulance crews working South Western Ambulance Service are to go on strike over pay and staffing on Wednesday 21 December.
The pre-Christmas date coincides with action being planned by two other unions – GMB and Unite – with members in ambulances services in England.
The UNISON strike involving paramedics, emergency care assistants, ambulance technicians and other 999 crew members will run from midday to midnight.
UNISON is also about to begin reballoting around 13,000 NHS staff working for ten trusts and ambulance services where turnout in the recent strike vote fell just short of the threshold required by law.
Commenting on the pre-Christmas strike, UNISON head of health Sara Gorton said: “The government will only have itself to blame if there are strikes in the NHS before Christmas.
“Ambulance staff and their health colleagues don’t want to inconvenience anyone. But ministers are refusing to do the one thing that could prevent disruption – that’s start genuine talks about pay.
“Wages are too low to stop health workers quitting the NHS. As more and more hand in their notice, there are fewer staff left to care for patients. The public knows that’s the reason behind lengthy waits at A&E, growing ambulance delays, postponed operations and cancelled clinics.
“Threatened NHS strikes in Scotland were called off because ministers there understand higher wages and improved staffing levels go hand in hand. Unfortunately, the penny’s yet to drop for the Westminster government.”
Senior managers in the five ambulance services and two NHS trusts are due to receive formal notification of the strike and will draw up emergency cover plans to put to the unions taking action.