Nurses and ambulance staff stepped up their demands for better pay Monday to combat the UK's cost of living crisis by launching their biggest round of health service strikes.

The stoppages -- part of a wave of industrial action across the UK economy -- saw nurses and paramedics go on strike on the same day for the first time on Monday.

Striking staff outside St Thomas' Hospital in central London waved placards and chanted "Safer staffing saves lives" and "Claps don't pay the bills", a reference to the daily national applause they received from the public during the coronavirus pandemic.

The healthcare workers say their wages have failed to keep up with inflation over the past decade, leaving them unable to pay their bills amid spiralling fuel, food and housing costs.

They warn that qualified nurses are quitting in droves due to the financial pressures resulting in understaffing that endangers patient care.

"We're run off our feet 24/7, breaking our backs doing the jobs of three people," said trainee nursing associate Victoria Busk, who works on a trauma ward at the Queen Elizabeth Hospital in Birmingham, central England.

"I love my job, I love the work I do, making a difference to patients. But I can't imagine doing this until I'm in my 60s," she said.

Last week, half a million people including teachers, transport workers and Border Force staff at UK air and seaports also stopped work over pay.

The Royal College of Nursing (RCN) union has said Monday's strike affects nurses in around a third of hospital trusts in England and most of Wales.

- 'Work for peanuts' -

The ambulance staff strike only affects England, however, after paramedics in Wales called off their planned action following an improved pay offer.

"Every time you go on a shift, it's dangerous due to low staffing," said Angela Unufe on a picket line outside the Queen's Medical Centre in Nottingham, also in central England.

The former nurse with the state-funded National Health Service now works as a ward manager at a private mental health clinic.

"It's got to a situation where as managers we have to fill in for nurses who are not on shift, because we can't get the nurses because there are no nurses there, as no one wants to work for peanuts," she said.

Health minister Maria Caulfield, who is also a nurse, said she sympathised with striking health service staff but argued that big pay hikes could not be afforded.

"I'm an RCN member myself, so I sit in both camps, if you like. Absolutely, I have a lot of sympathy," she told GB News.

"But we also have a responsibility to the taxpayer... we just can't afford inflation-busting pay rises that the unions are currently demanding."

British Prime Minister Rishi Sunak has called for pay rises to be "reasonable" and affordable", warning that big pay awards will jeopardise attempts to tame inflation.

Health Secretary Steve Barclay had urged unions to call off Monday's action.

"The Governor of the Bank of England warned if we try to beat inflation with high pay rises, it will only get worse and people would not be better off," he said.