Hospitals paid up to £3,200 for doctors to cover shifts in accident and emergency departments over Christmas and the New Year, new figures suggest.
Data obtained by Sky News through a Freedom of Information request also showed more than half the shifts during that period in some NHS hospital trusts were covered by locum doctors, with four trusts paying more than £2,000.
The highest amount paid was £3,258 by United Lincolnshire NHS Trust for a doctor to work for 24 hours, while Royal Berkshire NHS Trust paid £1,875 to an agency for a nurse to work a single shift, according to the figures.
Dr Clifford Mann, president of the Royal College of Emergency Medicine, told the broadcaster: "Market forces really are quite extreme currently, with the lack of permanent people to employ.
"It means hospitals are desperate to try to find people to fill these slots and are having to pay super premium rates for that to happen.
"It can be very demoralising to be working alongside somebody with much less experience, much more junior, who is earning a multiple income compared to you in terms of the pounds paid per hour."
A total of 75 of 140 hospital trust responded to the request, asking for data on staffing of accident and emergency departments between December 24 last year and January 1.
Airedale NHS Foundation Trust filled 71% of shifts with locum doctors during that period, while locums worked 58% of shifts at Heart of England NHS Foundation Trust and 52% at Royal Bolton Hospital.
This winter has seen an unprecedented demand on A&E services, with two weeks in December having the two highest attendance figures ever recorded for a winter period.
Last month, details uncovered by the Royal College of Nursing (RCN) estimated the NHS is on course to spend £1 billion on agency nursing staff by the end of the year due to a "payday loan attitude towards workforce planning".