Boris Johnson is set to lift Covid restrictions across England on Monday despite Downing Street conceding concerns over rapidly rising case numbers as more than 1,200 international scientists and health experts urged the government to scrap the “dangerous experiment” of “freedom day”.

New daily infections in the UK broke the 50,000 threshold on Friday for the first time since mid-January and official figures showed one in 95 people in England are estimated to have the virus – more than quadruple the rate in the middle of June, when the prime minister set 19 July for lifting most of the country’s last infection control measures.

A No 10 source said that “in terms of case numbers and projections” the picture was now “worrying”, with the UK over halfway to the 100,000 daily infections predicted by the health secretary, Sajid Javid, after curbs are lifted. Johnson had warned of 50,000 daily cases by 19 July but said the link with hospital admissions and deaths was all but broken.