NHS leaders have warned that strike action is making it “more difficult” for the health service to tackle the backlog of care.

The comments were made as NHS England said there were 7,600 cancellations in acute care as a result of the 28-hour strike by members of the Royal College of Nursing (RCN).

The numbers are lower than previous strikes due to the planned action taking place on Sunday into the early May Bank Holiday Monday, when traditionally fewer operations would have been scheduled compared to weekdays.

There’s no doubt that each round of industrial action makes it more difficult for the NHS to tackle the backlog

The figures may also include some postponements as a result of strike action by some members of the union Unite.

Overall the figures show that on May 1 and 2 – when certain Unite members were on strike – more than 11,000 appointments and operations were postponed across hospitals, community care and mental health services in England.

The data, released by NHS England, also shows that at least 5,000 staff joined picket lines on May 1, but many hospitals failed to report workforce figures so the figure is likely to be much higher.

NHS England’s deputy chief nurse, Charlotte McArdle, said: “Despite the extensive efforts of NHS staff to keep patients safe and limit disruption amid the loss of thousands of vital nursing staff, this weekend’s industrial action has inevitably had a very significant impact for patients and staff.

“Across the NHS we have now seen more than half a million appointments and procedures rescheduled over the last six months as a result of strikes from staff in a range of NHS roles – and with each strike, it is becoming harder.

“Our staff are doing all they possibly can to manage the disruption and deliver rescheduled appointments as quickly as possible, but there’s no doubt that each round of industrial action makes it more difficult for the NHS to tackle the backlog.”

An estimated 7.22 million people were waiting to start routine hospital treatment at the end of February, the highest total since records began in 2007, according to figures from NHS England.

The news comes as nurses warned that strikes could continue until Christmas after rejecting the Government’s revised pay offer.

Because the majority of unions representing staff on the Agenda for Change contract voted in favour of the deal, the NHS Staff Council was able to recommend that the Department of Health should implement the pay offer on Tuesday.

Health Secretary Steve Barclay warned the RCN the deal was the “final offer” but the union vowed to ballot members later this month as it warned that strikes could take place across the whole NHS in England between June and December.

An RCN spokesperson said: “The impact on patients is the hardest part and nursing staff are apologetic about the situation for individual patients affected. We are taking this action, however, because every day nursing staff and patients are suffering as staff shortages affect patient safety.

“Patients and the public know that and their support is appreciated and not taken for granted.

“This campaign has always been about patients and a safe NHS.

“The Government will never tackle the backlog without nursing staff nor fill the record number of unfilled nurse jobs without paying them fairly.”

NHS Providers deputy chief executive Saffron Cordery said: “We’ve now seen over 542,000 patient appointments delayed due to strike action over the past six months.

“Industrial action has piled even more pressure on overstretched services already grappling with a chronic capacity crunch, soaring demand and widespread staff shortages, slowing down hard-won progress in tackling record care backlogs.

“While leaders across the NHS hope yesterday’s acceptance of a new pay deal signals an end to the most disruptive period of industrial action in NHS history, they also know more strikes could be on the horizon if talks with junior doctors, nurses and others fail.

“The number of patients who face having their care disrupted will keep rising unless the Government finds a way to sit down with unions resolve these ongoing disputes.”