Unite the Union has announced 1,500 ambulance workers will strike on six extra days across February and March.
Staff across multiple ambulance trusts will strike on 17, 20 and 22 February and 6 and 20 March, Unite told the BBC.
Unite workers will also join nurses and ambulance staff represented by the GMB striking on 6 February in the biggest NHS walkout in this dispute.
A health department spokesman said it is “continuing to have constructive discussions” with unions about pay.
Unite General Secretary Sharon Graham told BBC’s Political Thinking podcast staff were “fighting for the NHS”.
Ms Graham said: “People are dying as we speak because of waiting times and the clogging up of the NHS.”
She called on Rishi Sunak to personally intervene on pay negotiations.
“If they don’t solve the pay crisis, they can’t solve the crisis of the workforce, which means that the NHS is on its knees,” she said.
The Unite union has announced a total of 10 new strike dates for its ambulance workers over the next two months, in an escalation of the dispute over pay.
Ambulance trust workers will be striking on:
- Thursday 26 January in Northern Ireland
- Monday 6 February in North West, North East, West Midlands, East Midlands and Wales
- Thursday 16 February in Northern Ireland
- Friday 17 February in West Midlands, Northern Ireland.
- Monday 20 February in East Midlands, North East and Wales
- Wednesday 22 February in North West
- Thursday 23 February in Northern Ireland
- Friday 24 February in Northern Ireland
- Monday 6 March in North West, North East, West Midlands, East Midlands and Wales
- Monday 20 March in North West, North East,West Midlands, East Midlands and Wales
Four of the new dates have been announced to coincide with mass walkouts of ambulance staff represented by the GMB.
This means walkouts by staff including paramedics, call handlers and support workers will take place in eight of the 10 English ambulance services along with the national Welsh service will take place on 6 February and 6 and 20 March.
On Monday, the Royal College of Nursing (RCN), set 6 and 7 February as the dates for its biggest strike to date, involving more than a third of services in England and all but one health board in Wales.
Under trade union laws, all unions will have to provide emergency cover.
Ms Graham said workers will ensure “proper minimum cover because that is something that’s really important to us”.
“Nobody wants lives to be lost,” she added.
But the governments in England and Wales have given NHS staff an average of 4.75%, with everyone guaranteed at least £1,400 – as recommended by the independent NHS Pay Review Body.
That is less than half the rate of inflation, although latest figures show the rate at which prices are rising has started to slow.
Meanwhile, patients are being warned to expect widespread disruption to services on Wednesday and Thursday because of the RCN walkout.
The government has made it clear it is not willing to move on this year’s pay award.
One option being explored by Health Secretary Steve Barclay is backdating the 2023-24 rise to January. It would normally kick in in April.
The Treasury has not agreed to the idea.
This has already been tabled in Scotland, leading to NHS strikes being halted for further negotiations – although staff there received a 7.5% pay rise this year.
A Department of Health and Social Care spokesperson said: “It is disappointing some union members are going ahead with further strikes at a time when the NHS is already under huge pressure from Covid, flu and tackling the backlog.
“The Health and Social Care Secretary is continuing to have constructive discussions with unions about the 2023/24 pay review process and what is affordable and fair.”