The surveys, carried out by Unison, reveal healthcare workers who do clinical jobs said not enough staff were present to deliver safe care on 69% of shifts.

The proportion has risen from 63% in 2023, when the research was previously carried out.

The findings are based on more than 1,400 shifts completed at over 40 hospital sites by clinical staff in England, Wales and Northern Ireland.

Staff reported the highest proportion of safety concerns after shifts on maternity wards (81%), in rehabilitation units helping people recover from injury, illness or disability (81%), or those looking after the elderly (82%).

A ‘red flag' event, involving a serious risk to safety, occurred on 56% of all shifts, but these were significantly more common where the shifts were not thought to be sufficiently staffed (67%) than those that were (16%).

A delay greater than 30 minutes in providing pain relief was reported on 54% of ‘unsafe' shifts, compared with 12% where enough staff were present.

Around three in five workers (64%) reported staffing gaps to employers, a fall from 71% in 2023. For those that did so, only 21% said they received a satisfactory response from their employer on how they would address the staffing issue to ensure safe patient care, which was down from 25% in 2023.

For those staff who didn't report concerns, 54% said they weren't confident their employer would act, so they did nothing.

Unison national nursing officer, Stuart Tuckwood, said: ‘These figures show staffing levels across the health service are alarmingly low on a regular basis.

‘Nursing staff are often unable to provide vital care or administer pain relief to their patients on time.

‘Workers are desperate for help from their employers, but there's little action when they report their concerns.

‘These figures should be a wake-up call for health service leaders given the state of NHS finances and talk of cuts. Urgent investment is needed in hospital staffing to ensure patients are kept safe.'