Britain on Friday “put the brakes on” easing lockdown measures and imposed new rules on millions of households in northern England, following concerns over a spike in coronavirus infections.

The reopening of high-risk activities such as casinos, bowling alleys and skating rinks, which was meant to begin on Saturday, will be delayed until at least August 15, as will the reintroduction of indoor performances and pilot schemes of larger crowds at sporting events, Boris Johnson announced.

“I have said our plan to reopen society and the economy is conditional.. that we would not hesitate to put the brakes on if required. Our assessment is that we should now squeeze that brake pedal,” the Prime Minister said in a Downing Street briefing.

Johnson, who earlier this week warned of a “second wave” of cases in Europe, added that Britain “cannot be complacent” about increasing infection numbers.

“We take this action with a heavy heart, but we can see increasing rates of COVID across Europe and are determined to do whatever is necessary to keep people safe,” Hancock said on Twitter.

Government data released Friday showed there was “some evidence that the incidence of new infections has increased in recent weeks” in England.

However, Chief Medical Officer Chris Whitty said “I don’t think it is helpful” to talk yet of a second wave sweeping across Europe.

The local measures came into effect at midnight (2300 GMT Thursday), just hours after being announced.

Andy Burnham, the mayor of Manchester, backed the measures due to an increase in infections.

“The picture in Greater Manchester has changed over the last seven days,” he told the BBC.

“We have a rise in nine out of the 10 boroughs, the reality on the ground is changing.”