A shortage of doctors and nurses means hospitals are routinely breaching new rules designd to reduce spending on agency staff.
A cap on agency spending has been breached 60,000 times since November after NHS trusts were forced to fork out for temporary workers to avoid wards being dangerously under-staffed.
Mid Yorkshire Hospitals Trust, which runs Pinderfields, Pontefract and Dewsbury hospitals, has had to breach the agency cap 132 times a week on average, according to research by industry magazine Nursing Times.
The cap on hourly pay rates was also being breached 115 times on average at Calderdale and Huddersfield hospitals.
The figures, revealed after the government launched a crackdown on “rip-off” spending on agency nurses and locum doctors, have led to calls for more investment in recruitment instead of short-term spending targets.
Glenn Turp, Yorkshire and Humber director for the Royal College of Nursing (RCN), said: “Trusts are right to put patient safety first rather than arbitrary, nationally set financial targets.
“But what this is really about is a national failure of workforce planning and pay, terms and conditions failing to attract and retain sufficient permanent staff.
“The NHS has relied on short-term agency staff to plug gaps for many years and the problem won’t be fixed overnight.”
In November trusts were told not to pay agency workers more than double the wages of permanent staff. That was reduced to 75 per cent last month and will be 55 per cent from April in a further tightening of the rules.
Breaches of the rules are allowed on “exceptional safety grounds”.
Mr Turp added: “NHS Trusts who are prepared to stand up for patient safety, rather than sticking to the cap should be congratulated.
“But as this data shows, this is an urgent problem because it’s not an effective or sensible way to spend money in the longer term and it is not sustainable.”
Last year health secretary Jeremy Hunt said the agency cap would end exorbitant fees and save £1bn over the next three years.
But so far more than 20 NHS trusts have breached the agency cap more than 100 times a week on average, according to Nursing Times.
One NHS trust, Nottingham University Hospitals, was breaching the rules at an average of more than 400 times a week.