Ministers are being warned of a mounting workforce crisis in England’s hospitals as they struggle to recruit staff for tens of thousands of nursing vacancies, with one in five nursing posts on some wards now unfilled.

Hospital leaders say the nursing shortfall has been worsened by a collapse in the numbers of recruits from Europe, including Spain and Italy.

The most recent NHS figures reveal there are about 39,000 vacancies for registered nurses in England, with one in 10 nursing posts unfilled on acute wards in London and one in five nursing posts empty on mental health wards in the south-east.

The number of nurses from the European Economic Area joining the Nursing and Midwifery Council register has fallen more than 90%, from 9,389 in the year to 31 March 2016 to 810 in the year to 31 March 2021.

Thousands of nursing shifts each week cannot be filled because of staff shortages, according to hospital safe staffing reports seen by the Observer.

The prime minister, Boris Johnson, is already under pressure over worker shortages in the UK after Brexit, from lorry drivers to farm workers. Concerns among health bosses about the impact on patient care of acute staff shortages are revealed as experts warned last week that flu could kill up to 60,000 this winter.

NHS trusts are being paid by NHS England up to £7,000 for each vacant post to try to recruit nurses from overseas countries including India and the Philippines.

Patricia Marquis, England director for the Royal College of Nursing (RCN), said: “There just aren’t enough staff to deliver the care that is needed, and we now have a nursing workforce crisis. We should never have got into a position where we were so dependent on international nurses. We are on a knife-edge.”

Hospital trusts struggling to fill nursing posts include:

University Hospitals of North Midlands NHS trust – which runs Royal Stoke university hospital and Stafford’s county hospital – and which has reported 401 unfilled nursing posts to its board, a vacancy rate of 12%. The trust temporarily suspended non-emergency operations last month because of high demand and staff shortages. It is recruiting nurses from overseas, including from India and Ghana.

Leeds Teaching Hospitals NHS trust, which has reported nearly 700 vacancies for nurses, midwives and operating department practitioners, a vacancy rate of 13%. It postponed 287 operations in July and August and appealed last weekend for nurses to work extra shifts because of “staffing shortfalls in our critical care wards”.

Mid and South Essex NHS foundation trust, with a 17% vacancy rate for nurses, one of the highest in the country. It has 2,269 full-time clinical and non-clinical vacancies. The trust reported that over the summer up to 1,850 patients a month were waiting longer than four hours in A&E because of staff shortages.

A survey by the union Unite of 188 critical care staff at Guy’s and St Thomas’ NHS foundation trust has uncovered staff concerns of “chronic” nursing shortages and risks to patient safety. Nine out of 10 staff reported understaffing in their department on every shift.

Dave Carr, 58, a critical care nurse at St Thomas’ hospital and a Unite representative, said: “I work in intensive care for patients recovering from surgery and we need up to 11 nurses on that shift, one for each patient. We regularly only have three or four of our own nurses available and have to borrow nurses from other areas or get temporary staff. Staff are absolutely wrecked. More than 100 nurses have left the trust in the last 10 months.”

Shelley Pearce, 34, an accident and emergency nurse and RCN workplace representative in southern England, said nurses from Europe endured abuse from some members of the public after the Brexit referendum. She said: “I can quite understand why some made a decision to go home because they didn’t seem to be wanted.”

The government has pledged to increase the number of NHS nurses by 50,000 by 2025. NHS England announced £28m of funding in September last year to recruit nurses from overseas to help pay for accommodation, flights and quarantine. The upfront cost of recruiting a nurse from overseas is between £10,000 and £12,000.

By comparison, it takes three years to train a nurse in the UK and costs from £50,000 to £70,000. The government does not pay tuition fees, but provides maintenance grants worth at least £5,000 a year.

There is a global shortage of nurses, and consequently there has been criticism of trusts recruiting from overseas instead of training more UK staff. Even the new care and mental health minister, Gillian Keegan, is reported to have called it “unbelievably inefficient and also wrong and just bizarre”.

Despite this, a report by the Nuffield Trust thinktank commissioned by the NHS and published last week, said significant overseas recruitment would be required if the government nursing target was to be met. Saffron Cordery, deputy chief executive of NHS Providers, called for a fully costed workforce plan in the government’s spending review this month.

She said: “We’ve had workforce shortages for many years, and we’ve seen that exacerbated by Brexit. The workforce is the engine of any hospital and when you have shifts that aren’t filled, that’s a huge challenge.”

Danny Mortimer, chief executive of NHS Employers, part of the NHS Confederation, said: “We have experienced the pressure we would usually see in the winter months over the summer. Many staff are predicting that this will be one of the most difficult winters the NHS has ever faced.”

A survey of more than 1,000 NHS staff by the Healthcare Workers’ Foundation, a charity that supports health service employees, found 73% considered leaving in the last year. Nearly one in three frontline staff said they were likely to leave in the next year.

The total number of full-time equivalent vacancies in the NHS in England has increased from 83,203 in June 2020 to 93,806 in June 2021, according to figures from NHS Digital, the government’s health and information centre. Over the same period, nursing post vacancies rose from 37,760 to 38,952.

Hospital trusts say they are recruiting staff from overseas to help fill posts. University Hospitals of North Midlands NHS trust said it had recently hired nearly 300 extra nurses, including 93 from overseas. Leeds teaching hospitals NHS trust said staffing was an “ongoing challenge”, but it was successfully recruiting new staff. Mid and South Essex NHS foundation trust said its gaps were filled by agency and temporary staff.

A spokesperson for Guy’s and St Thomas’ NHS foundation trust confirmed 118 nurses left this year, but said 97 started and another 30 were going through pre-employment checks. They said the trust was listening to all concerns raised by staff: “The safety of our patients and wellbeing of our staff are our top priorities. We are investing in recruiting more nurses, as well as continuing to provide extensive health and wellbeing support to our staff.”

Health experts say the overall NHS workforce is growing, but not enough to keep up with demand, and the proportion of unfilled jobs across NHS England has grown over the year.

The NHS said: “The NHS is committed to reducing nursing vacancies, including through international recruitment, and increasing wellbeing support for existing staff to boost retention.

“The nursing and midwifery workforce grew by over 2.7% over the past year with over 330,000 extra full-time staff delivering care, and 80,000 people across the country applied for a nursing course this year.”

A Department of Health and Social Care spokesperson said: “We are seeing record numbers of nurses working in the NHS and applications to study nursing and midwifery have risen by 21% this year alone. We will continue to support our NHS workforce to grow to tackle the backlog, with 50,000 more nurses by the end of this parliament.

“We are working closely with Health Education England, NHS England, Skills for Care and the wider sector to make sure we have staff with the right skills up and down the country. This includes improving retention, investing in and diversifying our training pipeline, and continuing to ethically recruit from overseas.”