A hospital is set to see more porters, cleaners and caterers take industrial action after members of a second union joined a dispute over bonuses linked to work carried out in the Covid pandemic.
Unite members at Russells Hall Hospital in Dudley had already been walking out since December.
It follows a refusal by their employer Mitie to pay a bonus to staff who worked through the pandemic period.
Now Unison members are to stage their own walk-outs over Mitie's stance.
The row centres on bonus sums, starting from £1,655, for staff employed directly by the NHS. The lump sums were based on pay.
Mitie said it was disappointed with the decision of Unison members.
The company took over from Interserve as the hospital's external employer of facilities staff including porters, receptionists, restaurant workers and hospital cleaners.
Hospital bosses said they were assessing the situation after being made aware of the developments.
About 450 workers could be involved and twice weekly action is expected to disrupt services.
'Huge ballot result'
Unison West Midlands regional organiser Ollie Hopkins said nobody working in the NHS wanted to strike, but it was "the inaction of Mitie" that had led to a "huge ballot result".
Unite said it was pleased Unison members voted to join the action and would be on picket lines on 23 February.
In a statement, Mitie said: "We're disappointed that Unison members have voted to take industrial action, given we've kept our colleagues regularly updated that we are still awaiting a response from government on our funding application.
"As always, our priority is to ensure that our services continue to be delivered and we have strong contingencies in place to avoid any disruption to patient care."
The company stated it was "an award-winning employer, committed to offering industry leading benefits to all our colleagues".