The NHS is facing the "biggest pressure in its history" from a backlog potentially twice as big as previously feared, Matt Hancock has warned.

On Thursday, the Health Secretary told hospitals to brace for a flood of up to 12.2 million people in need of elective procedures such as hip, knee and eye operations. This includes 5.1 million patients currently on waiting lists.

Health bosses believe there could be a further 7.1 million who stayed away during the Covid pandemic but who will come forward demanding treatment, Mr Hancock revealed.

He said that even with the NHS "running at 100 per cent", coping with this total would be the greatest challenge the service had yet encountered.

"I’m totally open about the fact that we fully expect the formally declared backlog to rise because there is another backlog out there – it just isn’t in the numbers," he told the NHS Confederation conference.

Waiting lists could take years to clear

NHS leaders have already warned that it could take five years to clear the total of patients currently on waiting lists and those who have so far delayed seeking help due to the pandemic.

It means people could wait years for procedures that would normally be carried out in a matter of months.

Mr Hancock said the list of patients currently waiting over a year for treatment had recently gone down but warned: "We can all see demand returning and our emergency departments filling up. We know that there are already 5.1 million people in England waiting for care at this moment. 

"We know the 5.1 million doesn’t yet include the returning demand of people who have not come forward for care during the pandemic but are now regaining the confidence to approach the NHS.

"Even with the system running at 100 per cent, even with everybody working incredibly hard for that demand comes back, we would have the biggest pressure on the NHS in its history."

The NHS has recruited more than 5,600 extra doctors and 10,800 nurses since last March in a bid to cope with the extra demand. Meanwhile in March the Government pledged a further £7 billion in funding.

The comments come amid the row sparked by Dominic Cummings over Mr Hancock’s performance during the early weeks of the pandemic.

Boris Johnson’s former chief adviser said the health secretary should be sacked for "lying" that the NHS was open to all who needed it. Numerous patient groups have since rejected that assertion.

Speaking at the same conference on Thursday, Prof Chris Whitty, England’s chief medical officer, said the current wave of cases would "definitely translate into further hospitalisations".

He added that because there was minimal flu last winter it will be back this winter "unless the Covid situation is so bad that everybody has started to go back to essentially minimising their social contacts again".

"So either we will have a very significant Covid surge, people will minimise their contacts and we will have less respiratory viruses, or people will be back to a more normal life, there will be some Covid but on top of that we will go back to having a flu surge, an RSV surge in children, and so on," he said.