The government is reportedly keeping a “close eye” on a descendant of the Covid Delta variant that is being seen in a growing number of cases sparking fears of a return to coronavirus restrictions.

Downing street said was monitoring the AY4.2 variant, but insisted there was no evidence it spreads more easily.

The Prime Minister’s official spokesman said: “It’s something we’re keeping a very close eye on.

“There’s no evidence to suggest that this variant … the AY4.2 one … is more easily spread.

“There’s no evidence for that, but as you would expect we’re monitoring it closely and won’t hesitate to take action if necessary.”

Downing Street warns of ‘challenging’ months ahead

It comes as Britons have been warned the coming months will be “challenging” as coronavirus cases reached the highest daily level since mid-July.

Downing Street said an increase in coronavirus cases had been expected over the winter and the Government would keep a “close watch” on the situation.

Epidemiologist and government adviser Professor Andrew Hayward said the situation was “concerning” and there was “huge potential for the NHS to come under a lot of pressure”.

Government data up to Monday shows there have been a further 49,156 lab-confirmed Covid-19 cases in the UK. This is the highest number of daily reported cases since July 17.

Another 45 people had died within 28 days of testing positive for Covid-19 as of Monday, bringing the UK total to 138,629.

Boris Johnson issues statement over rise in Covid rates

The Prime Minister’s official spokesman said: “We obviously keep very close watch on the latest statistics.

“We always knew the coming months would be challenging.

“What we are seeing is case rates, hospitalisations and deaths still broadly in line with the modelling as set out a few months back now.

“The vaccination programme will continue to be our first line of defence, along with new treatments, testing and public health advice.

“But we will obviously keep a close watch on cases.

“But it is thanks to our vaccination programme that we are able to substantially break the link between cases, hospitalisations and deaths.”