The Wye Valley NHS Trust could have faced fines of £46,500 last year for breaking rules which ban mixed-sex wards.

But enforcement of the penalties is left to individual Clinical Commissioning Groups, which plan and buy healthcare from trusts, so they could have been waived.

A leading health think tank says rising demand is leaving staff with no choice but to break the rules – which can carry a hefty penalty.

The Wye Valley NHS Trust recorded 186 breaches of mixed-sex accommodation rules during 2019, NHS figures show.

Trusts are supposed to be fined £250 per patient each time they break the rules, with NHS England guidance stating they should have a "zero-tolerance" approach.

This would mean the Wye Valley NHS Trust faced fines of £46,500 over the course of the year.

December saw the number of breaches recorded across England hit the highest level for the same month since 2010, with more than 2,000 incidents – an increase of 20% in one year.

Nigel Edwards, chief executive of health think tank the Nuffield Trust, said increasingly busy hospitals were struggling to stick to the rules.

He said: "These rises in mixed sex accommodation breaches, which will be upsetting for patients, haven't happened because the NHS has just stopped trying.

"Rather, we're now seeing a very high proportion of beds full nearly all the time, leaving staff no choice sometimes but to put people onto a ward for the wrong sex or no ward at all.

"Unfortunately, there tends to be even less space available in winter, so pressure may still get worse – in previous years, breaches have peaked in January or February."

The ban applies to sleeping accommodation, which includes any area where patients are admitted on beds or trolleys even if they do not stay overnight.

It does not include instances where mixed accommodation is considered justified, such as in intensive care.

Lucy Watson, chair of the Patient's Association charity, said failing to follow the rules could cause additional anxiety for people already worried about being in hospital.

"We are very concerned that so many people are still being placed in inappropriate hospital accommodation, many years after mixed-sex wards were supposedly abolished," she said.

"Patients deserve to be treated with dignity, and at a time when many will be feeling frail or vulnerable, it is vital that they feel some sense of privacy and safety.

"Patients shouldn't find themselves in a bed next to a member of the opposite sex, particularly if they need to use a bedpan, or have intimate care."

An NHS England spokesman said: "The vast majority of trusts have completely eliminated breaches, and at just 0.1% of hospital stays they remain extremely rare in the context of the rising number of people who are admitted to hospital every month.

"But the ambition remains to keep the number of times that this happens to an absolute minimum, and the Government's commitment to increase the number of nurses by 50,000 and invest in new and expanded beds and facilities will be crucial in achieving this over the coming years."