British Prime Minister Boris Johnson is back at his Downing St office after recovering from COVID-19.

Mr Johnson arrived back at No.10 Downing St on Sunday evening, after spending a week in hospital and two weeks recovering in his country home.

He returned to a growing chorus of calls from senior Conservative Party figures to begin easing the UK’s lockdown amid mounting economic costs.

Earlier, Foreign Secretary Dominic Raab insisted there could be no immediate relaxation, saying the outbreak was still at a “delicate and dangerous” stage.

Mr Johnson is expected to chair a Monday morning meeting of the government’s COVID-19 war cabinet.

Mr Raab said Mr Johnson was “raring to go”.

But the foreign secretary said the government would proceed “cautiously” in order to avoid a second peak in the outbreak.

“We need to make sure that the next steps are sure-footed, which is why we are proceeding very cautiously and we are sticking to the scientific advice,” he told Sky News on Sunday.

Mr Johnson was taken to St Thomas’s Hospital in central London suffering from COVID-19 symptoms on April 5, and spent three days in intensive care.

-with AAP