Britain’s Christmas lockdown could be reviewed within days of the war, an NHS chief has warned.

Chris Hopson, chief executive of NHS providers, wrote an urgent letter to Boris Johnson warning that any relaxation could “trigger a third wave.”

The agency, which represents all hospital trusts in England, has stopped short of claiming that the five-day Christmas bubble system is now being reviewed.

But Mr Hopson told Sky News: “We are not calling for a change in regulation at this time, but I think we need to look into the next few days.”

His letter to the prime minister added: “Trusted leaders fear that if the infection rate is so high at the moment, the easing of restrictions will accelerate the third wave.”

Wales’ first minister announced this week that ministers had met to discuss whether to change Christmas rules but had not made a decision.

Ministers plan to review England’s lockdown level on Wednesday. And people across the UK will be allowed to gather the three families together for the Christmas bubble from 23-27 December.

But Mr Hopson warned people that only older relatives were allowed to visit, which did not mean it would be safe.

“We need a much better debate about the risks of what will happen at Christmas,” he told Akash. “We are very worried.”

He added: “Everyone is currently working on the premise that there are rules so if they observe the rules they will be fine and that is not the case.

“Any additional social contact, especially with people at risk for the virus, is probably a real problem.”

Mr. Hopson today requested Mr. Johnson not to lower any territory just before Christmas.

He told Sky News that the NHS has 10,000 fewer beds than last year due to infection control measures – and 13,000 covid patients are in the remaining beds.

Mr Hopson said: “The town of Easter has sunny peaks, but we have a long way to go to get through the winter.”

The rules of social distance will be relaxed for five days between 23 and 27 December, so that family members are allowed to hug for the first month.

A government spokesman said the ministers “would not hesitate to take the necessary steps to protect the local population” and that the decision was based on the latest information.

“We have introduced strong local restrictions to protect the progress made during the national sanctions, to reduce the pressure on the NHS and ultimately save lives.”

“On top of our record NHS investments, this winter we will provide an additional £ 3 billion to sustain the growth of the independent sector and Nightingale Hospital and provide another 50 450 million to upgrade and expand A&S.”

On Saturday, the government said 599 more people had died in the UK within 28 days of testing positive for covid-19, with 21,502 more lab-confirmed cases of coronavirus.

Meanwhile, the health secretary has hinted that cities and villages will not be able to move the alert level by becoming “duplicated” from nearby coronavirus hotspots.

Matt Hancock said in a letter to Tory MPs that “narrow curve-outs” in lower-lying areas often “catch” or “exceed” high-level areas, according to the Daily Telegraph.

It comes after Sadiq Khan urged Londoners to follow social-distance measures and wear face covering during Christmas shopping this weekend.

Crowds thronged the shopping districts of major cities, including London’s Regent Street, on Saturday.

As the rate of infection increases, there are fears that the capital may be moving towards Tier 3 restrictions, which will seemingly shut down hospitality settings without exception.