The final stage of easing lockdown restrictions in England is to be delayed until July 19.
It means most remaining curbs on social contact will continue beyond June 21, when they had been due to be lifted.
Prime Minister Boris Johnson said there would be a review after two weeks and he was “confident” the delay would not need to be longer than four weeks.
Scientists advising the government had warned of a “significant resurgence” in people needing hospital treatment for Covid-19 if stage four of easing the lockdown went ahead on June 21.
The decision comes amid rising cases, driven by the more transmissible Delta variant, which was first identified in India.