A sharp deterioration in turnaround times and availability of Covid-19 tests in Britain saw the government admit there were challenges to its testing regime that it says has been swamped by demand amid a spike in cases.

The British government has been under intense pressure over the buckling of its promised “world-beating” system to test and trace coronavirus cases, meant to protect the country from a second wave of infection as schools reopened this month.

“There’s a challenge in testing,” UK health minister Matt Hancock said, adding that capacity for testing was growing. “The challenge is that demand has gone up faster.”