There is "huge concern" from NHS leaders that a four-day junior doctors strike next week will be the most disruptive walkout for the health service so far.

Up to a quarter of a million appointments and operations could be postponed, the NHS Confederation has warned, amid fears that patient safety could be jeopardised.

Health bosses have warned that the disruption could last for up to 10 or 11 days.

Dr Layla McCay, director of policy at the confederation, said they were more concerned by this bout of industrial action than any previous walkouts over the last few months.

Junior medics in England are striking from Tuesday but the British Medical Association (BMA) has said the government could still make a "credible offer" that would help to bring the dispute to an end.

Dr McCay told BBC Radio 4's Today Programme: "In the last junior doctors' strike, we saw about 175,000 appointments and operations having to be postponed.

"In terms of the disruption that we're anticipating this time, we reckon it could be up to about a quarter of a million so that is a huge amount of impact for patients up and down the country."

She added: "What we're hearing from our members who are health leaders across the whole system is that they are more concerned about this than they have been about any other strike.

"They think that the impact is going to be so significant that this one is likely to have an impact on patient safety and that is a huge concern for every healthcare leader."

"What we expect to see is really significantly diminished capacity within the health service with these junior doctors being out," she said.

The Department of Health and Social Care, headed by Steve Barclay, has insisted the BMA has to call off strike action before any negotiations can take place.

Dr Mike Greenhalgh, deputy co-chair of the BMA's Junior Doctors Committee, told BBC One's Breakfast show: "It's hard to negotiate when only one side is doing it and we're not getting anything back from the government on that front."

He added: "We're happy to meet at any time. We would still meet him over the bank holiday weekend before the industrial action next week.

"And if [Barclay] was to bring a credible offer to us, it could still, even at this late stage, avert action."

Dr Greenhalgh apologised to patients who have had operations or appointments cancelled and insisted patient safety would not be put at risk.

"Patient safety was maintained at the last strikes, and it will be in these strikes," he said.

The four days of strikes will run from 6.59am on Tuesday 11 April until 6.59am on Saturday 15 April.