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By Kate Whannel
Political reporter, BBC News
Rishi Sunak has insisted he will not back down against striking workers, as nurses walk out in England, Northern Ireland and Wales for a second day.
Nurses' union boss Pat Cullen has urged the prime minister to resolve the crisis before Christmas.
But there is no sign of a breakthrough between the sides.
The prime minister told The Mail he would rather accept widespread disruption than increase workers' pay, which he says would fuel inflation.
The UK is facing its biggest week of industrial in recent history in the run up to Christmas, with ambulance workers, customs and immigration staff, bus drivers, postal workers all staging walk outs.
The armed forces have been drafted in to cover some of the walk outs - but concern is growing about Wednesday's ambulance drivers in England and Wales, with a health minister warning people to avoid "risky activity".
Workers are calling for higher pay to help them cope with the rising cost of living, but there are also additional disputes over working conditions.
Mr Sunak is facing calls to reopen talks on nurses' pay and deal with the growing wave of strikes across the public services.
But he told The Mail: "I'm going to do what I think is right for the long-term interests of the country - combating inflation."
Ministers have also argued it would be wrong to unpick the wage levels, which were set by the pay review bodies earlier this year.
The prime minister said unions should instead focus on future pay negotiations adding: "We do need to think about what's the right approach for next year."
Speaking to the BBC's Today programme, Ms Cullen said she was "truly sorry" for every patient who would have their care disrupted during Tuesday's strikes.
"We would negotiate with government - again we won't dig in if they don't dig in.
"But we have no opportunity to do that because we can't get to a table to talk to government."
In a statement released ahead of the strikes, Ms Cullen said she believed the dispute could get "wrapped up by Christmas" if ministers engaged with union talks.
However, she warned that if the government wasn't "prepared to do the right thing" her union would have "no choice" but to continue striking in January.
The Royal College of Nursing has called for a 19% pay rise (5% above the RPI inflation rate) but the government has said this is unaffordable.
Ambulance staff - who are set to walk out on Wednesday - also want above-inflation pay rises, but have not set a specific figure.
Health Secretary Steve Barclay is due to meet health unions, however it is expected these talks will not touch on pay, but rather focus on how emergency care will be provided during the strikes.