Councils have been consulted on whether there is support for an immediate rollout of stricter coronavirus restrictions.

The UK Health and Security Agency (UKHSA) contacted local authorities on Friday to canvass the level of support for an "immediate rollout of the winter plan - plan B", according to the Observer.

The letter states it was urgently seeking the views of council chief executives and leaders on whether restrictions should be re-imposed.

Plan B measures would include "communicating clearly and urgently... that the level of risk has increased", including implementing vaccine passports for some places and bringing back mandatory face coverings in certain settings.

This comes as senior health figures warn the government that the NHS faces significant pressure should they not act to curb a rise in infections.

Professor Adam Finn, who is on the Joint Committee of Vaccination and Immunisation (JCVI), said Covid-19 hospital admissions and deaths are rising, and warned against complacency in what he said is a "worsening" situation.

"And they will go up as the number of cases go up because the virus will reach people who are vulnerable and who may get seriously ill," he told Trevor Phillips On Sunday on Sky News.

"So I think we can't be complacent about this. This is a worsening situation in an NHS which is already under enormous pressure."

Prof Finn said the biggest risk is amongst those who have not had any vaccine yet, including younger adults.

"Many of the hospitalised people we're seeing at the moment are in fact unimmunised people," he said.

Boris Johnson and the government have so far resisted suggestions that plan B should be implemented.

In England, most restrictions ended on July 19.

The UKHSA declined to comment on leaks, telling the Observer that it is part of the organisation's role to provide advice to the government.