A quarter of NHS workers are more likely to quit their job than a year ago because they are unhappy about their pay, frustrated by understaffing and exhausted by Covid-19, a survey suggests.

The findings have prompted warnings that the health service is facing a potential “deadly exodus” of key personnel just as it tries to restart normal care after the pandemic.

A representative poll of 1,006 health professionals across the UK by YouGov for the IPPR thinktank found that the pandemic has left one in four more likely to leave than a year ago. That includes 29% of nurses and midwives, occupations in which the NHS has major shortages.

Ministers must initiate a “new deal” for NHS staff that involves a decent pay rise, better benefits, more flexible working and fewer administrative tasks, the IPPR said.

“The last 12 months have stretched an already very thin workforce to breaking point. Many are exhausted, frustrated and in need of better support. If the government does not do right by them now, more many leave their jobs,” said Dr Parth Patel, an NHS doctor and IPPR research fellow who co-wrote its new report on how the NHS can retain and recruit more staff.

The apparently greater readiness to consider leaving means that as many as 330,000 staff could quit, the IPPR said.

“In reality many of these workers will not leave,” its report says. “But a highly dissatisfied and demoralised workforce is very bad news for patients and productivity. Even if only a fraction leave, it would significantly compound existing understaffing problems, particularly as those most likely to leave – nurses – are the group with the highest number of shortages,” it adds.

The IPPR report follows a warning last week by the NHS Confederation, which represents hospital trusts in England, that Boris Johnson will struggle to fulfil his pledge to increase the NHS nursing workforce by 50,000 by 2024 unless staff are given proper time off to recover from the pandemic.

Asked by the IPPR what their priorities were for improving their working lives, 70% of staff questioned said a pay rise – more than twice those who identified any other factor.

NHS trade unions, Labour and some of its own backbench MPs have criticised the government for offering staff only a 1% pay hike when the NHS in England had budgeted for 2.1%.

“This report should act as a wake-up call to government and force them to stop ignoring the warning signs of an exodus of nursing staff from the NHS.

“Ministers must now rethink their pay offer and put in proper support service for those who given so much in the last year,” said Prof Dame Donna Kinnair, the chief executive of the Royal College of Nursing. It has threatened to strike unless the 1% offer is improved.

Criticism of the government’s handling of Covid-19 is helping to drive the apparent readiness of NHS staff to consider leaving. Almost nine in 10 said slow government policy, for example being late to lockdown society, was a very or somewhat important reason why the UK has had one of the highest death rates in Europe from the pandemic. Almost 80% cited “an under-resourced NHS, with little ‘spare capacity’”.

A Department of Health and Social Care spokesperson said: “We recognise the pressure this pandemic has put on all health and social care staff and have put £15m into dedicated staff mental health support and launched a 24/7 helpline.

“There are record numbers of doctors and nurses working in our NHS with nearly 10,900 more nurses and almost 6,600 more doctors than last year. We are committed to supporting every one by further boosting recruitment, investing in staff, and backing the NHS with an extra £29bn in Covid funding over the next year.”