Nearly half of patients are waiting too long for non-urgent treatment at Royal Cornwall Hospitals Trust, new figures show, as disruption caused by the coronavirus pandemic continues.

With colder weather approaching, experts are warning that the NHS must be winter-proof to prevent seasonal flu and further Covid-19 outbreaks from bringing routine surgeries to a halt.

According to NHS rules, patients referred for non-urgent consultant-led elective care should start treatment within 18 weeks.

But NHS data shows 47 per cent of patients on the waiting list for elective operations or other treatment at Royal Cornwall Hospitals NHS Trust at the end of July had been waiting longer – up from 13% in the same month last year.

It means 12,531 patients had been waiting longer than the target time.

NHS trusts are normally expected to make sure no more than eight per cent of patients are left waiting beyond the 18-week maximum target.

But non-urgent elective operations – such as hip and knee replacements – were suspended during the height of lockdown to free up beds for coronavirus patients, leading to delayed care for many patients across England.

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Professor Neil Mortensen, president of the Royal College of Surgeons, said patients who have been waiting months for treatment "cannot afford to wait until next spring".

He added: “We urgently need to build up our hospital reserves if we are to see this winter through.

"Flu, together with continuing local Covid-19 outbreaks, must not bring surgery to a standstill again, or thousands more will suffer.”

Nationally, 2.2 million people were still waiting for treatment after 18 weeks in July – the highest number for a single month since records began in 2007.

At 47 per cent of those on the waiting list, it was also the worst performance on record.

Some 83,000 patients had been waiting for over a year, the most for any month in more than a decade.

The lengthy waits are a “timely reality check on the challenges facing NHS services” as they deal with a backlog of patients since the pandemic hit, Gbemi Babalola, senior analyst at The King’s Fund think tank, said.

Meanwhile, the Society for Acute Medicine has called on the Government to “publish full winter crisis planning proposals which include investment into staffing and estates to cope”.

Its president, Dr Susan Crossland, said: "The NHS is struggling hugely despite the drop in elective work and we are now seeing increased pressures with admissions creeping up.

“The reduction in acute beds is a major concern for us. We cannot allow corridor care to return."

Saffron Cordery, deputy chief executive of NHS Providers, said the focus should not be solely on what Covid-19 stopped the NHS from doing, and called for the hard work of frontline staff to be recognised.

She added: “We are in a much better place than many would have predicted a few months ago.

“The recovery from the peak of the pandemic was always going to require step by step increases in activity and the NHS is well on the way to restoring services.”