The NHS is facing a “hugely disrupted day” after tens of thousands of workers began the biggest walk out in the service’s history.

The Royal College of Nursing (RCN) said strikes will continue for “as long as it takes”, while Unite warned of a “constant cycle” of industrial action.

Union leaders implored the Government to act to prevent further strike action but ministers have insisted they cannot afford “inflation-busting pay rises”.

The NHS is expecting upheaval across England as nurses from the RCN stage walk-outs alongside GMB and Unite paramedics, call handlers and other staff at ambulance trusts.

It is the first time ambulance workers and nurses have walked out on the same day.

Nurses will strike again on Tuesday, ambulance workers again on Friday and physiotherapists on Thursday.

NHS leaders described the “most disruptive week of strikes to date” – but urged people to seek urgent and emergency care if they need it and attend appointments as planned unless they have been contacted in advance.

Unions in Wales largely suspended similar action after the Welsh government came forward with an improved pay offer on Friday.

Saffron Cordery, deputy chief executive of NHS Providers, which represents NHS trusts, told Sky News: “I think it’s going to be a hugely disrupted day across the NHS. It’s going to be incredibly challenging.

“With both nurses and ambulance staff out on strike today, and nurses again tomorrow – and we’ve got physiotherapist later in the week and some ambulance staff again on Friday – we’re planning for an incredibly disrupted week.”

She said hospital leaders will need to “step away” from day-to-day tasks, including clearing the backlog of care and implementing the Government’s new Urgent and Emergency Care plan.

“They will be focusing simply on getting through the next couple of days and that will have a knock-on effect on patients,” she said.

“This isn’t just about the here and now, it’s about the knock-on effect. What does it mean when someone has a procedure, a test, an operation, delayed for a number of days, a number of weeks? That will have an impact on them.”

While urgent and emergency care remains open, Ms Cordery said there could be an impact on cancer services in some parts of the country.

She urged the Government to negotiate with unions on 2022/23 pay.

“Well, I hope it ends by the Government coming around the table to negotiate a settlement for this year’s pay for NHS staff.

“I think that we need to recognise that NHS staff have faced soaring costs, cost of living has gone up, inflation has gone up, and the settlement from this year’s pay review body was made at a time when inflation wasn’t at the levels it’s at at the moment.

“So I think it’s really important that we focus on getting a deal for this year, as well as then thinking about what next year’s pay deal looks like.”

RCN general secretary Pat Cullen told the PA news agency: “Everyone can see the resilience of our nursing staff, these brilliant people that are standing on the picket lines today, losing another day’s pay. They are saying patients have had enough, they have had enough.

“They’re not willing to continue to see their NHS managing every day within a crisis.

“They’re trying to bring their NHS back from the brink and they will continue to do this for as long as this Government takes to listen to them.”

Speaking at a picket line outside St Mary’s Hospital in Paddington, west London, Ms Cullen added: “Hundreds of thousands of nurses take part in this ballot and they’ve given me the strongest mandate of any nursing profession throughout the world, so they will continue to do this for as long as it takes for this Government to actually wake up and listen to their voice and listen to their voice on behalf of patients and do the decent thing.”

She added: “We are in a situation today where this Government has chosen to punish the nurses of England instead of getting round a table and talking to me about pay in the same way as they’ve done in Wales and Scotland.”