Boris Johnson is warning that a second wave of coronavirus has arrived in the UK, as scientists reported the “widespread growth” of the virus across the country.

The Government’s Scientific Advisory Group for Emergencies (Sage) said the R number – representing the number of people an infected person will pass the virus to – has risen to between 1.1 and 1.4, meaning cases could rise very quickly.

As ministers announced tough new restrictions affecting 13.5 million people, Mr Johnson said they would “keep everything under review”.

“There’s no question, as I’ve said for several weeks now, that we could expect (and) are now seeing a second wave coming in,” he told reporters during a visit to the Vaccines Manufacturing Innovation Centre construction site near Oxford.

“We are seeing it in France, in Spain, across Europe – it has been absolutely, I’m afraid, inevitable we were going to see it in this country.”

Public Health England (PHE) warned that data published on Friday could be a sign of “far worse things to come”, as the Office for National Statistics (ONS) said cases are thought to have almost doubled in a week to 6,000-a-day in England.

East London and West Essex Guardian Series:

Boris Johnson during a visit to the Jenner Institute in Oxford, where he toured the laboratory and met scientists who are leading Covid-19 vaccine research. Photo: Kirsty Wigglesworth/PA

Kevin McConway, emeritus professor of applied statistics at the Open University, described the latest R figure as “undoubtedly concerning”.

He said: “Even at growth rates within the estimated range, the number of new cases could grow to high levels quickly if the interventions are not sufficiently effective.”

It comes as ministers discuss whether further national restrictions are needed, such as forcing pubs and restaurants to close at 10pm or curbs on people socialising.

The Prime Minister insisted that he did not want a second national lockdown, but said it was essential that people followed social distancing guidelines – including the new “rule of six”.

“But as we look at this particular curve and what is happening now, clearly we are going to keep everything under review. I don’t want to get into a second national lockdown at all, it is the last thing anybody wants,” he said.

“I don’t want to go into bigger lockdown measures at all, we want to keep schools open and it is fantastic the schools have gone back in the way they have. We want to keep the economy open as far as we possibly can, we want to keep businesses going.

“The only way we can do that is obviously if people follow the guidance.”