Up to 14 million people could be on NHS waiting lists in England by next autumn, new analysis suggests.

Currently, some five million are waiting for routine operations and procedures – many of whom are in pain.

But the Institute for Fiscal Studies has warned there is a huge hidden backlog of patients who are still yet to come forward for treatment.

The government pointed to the £1bn it had given to the NHS this year to clear the backlog.

There have been repeated warnings over the length of hospital waiting lists in England. A record number of patients are currently waiting for surgery – such as hip or knee replacements – with more than 385,000 patients waiting more than a year, compared to just 1,600 before the pandemic.

NHS waiting lists in England could more than double in the coming months, the health secretary has said.

Currently, some 5.3 million people are waiting for routine operations and procedures in England.

Sajid Javid told the Sunday Telegraph he was “shocked” when officials warned him that the backlog could reach 13 million patients.

But he added he was confident most remaining curbs would be lifted in England on 19 July.

Mr Javid, who became health secretary two weeks ago after his predecessor Matt Hancock resigned following an apology for breaking social-distancing rules, said waiting lists were his priority.

He told the Sunday Telegraph: “What shocked me the most is when I was told that the waiting list is going to get a lot worse before it gets better.

“It’s gone up from 3.5 million to 5.3 million as of today, and I said to the officials, so what do you mean ‘a lot worse’, thinking maybe it goes from 5.3 million to six million, seven million. They said no, it’s going to go up by millions… it could go as high as 13 million.

“Hearing that figure of 13 million, it has absolutely focused my mind, and it’s going to be one of my top priorities to deal with because we can’t have that.”

Among the solutions, Mr Javid said, would be to pay private healthcare providers to continue to treat NHS patients, and keeping virtual doctors’ appointments.

The waiting list for hospital treatment could soar to almost 10 million people by Christmas amid a huge backlog caused by coronavirus disrupting services, NHS leaders are warning.

Hospital bosses say that such a massive increase in England is a realistic prospect, given so many people have been unable to have surgery and crucial diagnostic tests in recent months while the NHS’s main priority has been minimising the damage from Covid-19.

The total number of people waiting to undergo a procedure in a hospital in England such as a hernia repair, cataract removal or hip or knee replacement stood at 4.4 million before the pandemic. It then fell to 4.2 million because in March GPs referred fewer patients for care to help hospitals tackle the pandemic and also because some patients were reluctant to risk getting infected by going into hospital.

However, the NHS Confederation estimates that it is likely to reach 9.8 million by the end of the year as a result of staff shortages and hospitals having to cap the number of patients they can treat at any one time because of strict physical distancing rules that reduce the number of beds available.

In a “pessimistic” scenario – which would result if a second wave of the virus emerges – the waiting list, comprising people who are meant to be treated within 18 weeks, could hit 10.8 million. And even under the confederation’s best-case “optimistic” scenario about 8.1 million people would be waiting.