London, April 27: British Prime Minister Boris Johnson on Monday will resume charge of the government's response to the coronavirus pandemic, a month after being diagnosed with the deadly disease that has claimed 20,732 lives in the UK.

Johnson, 55, had been recuperating from his intensive care treatment at a London hospital earlier this month after he contracted the deadly virus. He returned to 10 Downing Street on Sunday evening from his prime ministerial countryside retreat at Chequers, where he had been based since his discharge from St Thomas' Hospital on April 12. Boris Johnson, United Kingdom PM, Tests Positive For Coronavirus.

“It is hard to find the words to express my debt to the NHS [National Health Service] for saving my life,” he said, in his message to the medical team on leaving the hospital.

UK Foreign Secretary Dominic Raab, who has been deputising for the UK prime minister as the First Secretary of State during the leave of absence, described his boss' return as a “boost for the government and a boost for the country”. “He's raring to go,” Raab said.

Johnson resumes work amid growing pressure from within his own Conservative Party backbenchers as well the Opposition parties to set out a clear exit strategy to begin lifting the strict lockdown measures in place to curb the spread of the coronavirus.

"If there is a question over whether something is necessary or not, I think we should err on the side of openness and trying to make sure that more people can get on with their lives and more people can get on with getting back to their jobs," said Sir Graham Brady, the chair of the Tory party's influential backbench 1922 Committee.

Opposition Labour Party's shadow cabinet minister Rachel Reeves said the UK should "potentially" be following the example of other European countries like Belgium, Germany and Denmark, which have already signalled partial re-opening of some businesses and schools.

"We want to work with the government in bringing forward a plan and getting it right," she said.

Officials are reported to be working on a Singapore-style plan for passengers arriving at the UK sea and airports to be quarantined for 14 days as part of the second phase of the measures, which must be reviewed by law on May 7.

However, UK Environment Minister George Eustice seemed to dismiss the idea at the daily Downing Street briefing on Sunday.

“As we move to a new phase at some point in the future – we are not there yet – international travel could become a more significant part of the risk to manage," he said.

“At the moment, all of the evidence suggests it is only a tiny proportion of the cause of the coronavirus outbreak – if we got to that point, a number of measures would be considered but no decisions have been taken in this phase yet,” he added.

Johnson has meanwhile kept in contact with his ministers and officials and held his weekly audience by telephone with Queen Elizabeth II last week, indicating his readiness for full-time duties.

He held a long meeting with Raab and UK Chancellor Rishi Sunak on Friday ahead of his formal return, during which the senior team is believed to have thrashed out aspects of the next phase in the government's Covid-19 strategy.

The strict social distancing norms in place in the UK were imposed in a televised address by Johnson on March 23 and they require people to stay at home, shutting most businesses and preventing gatherings of more than two people.

The lockdown is intended to protect the state-funded NHS from being overwhelmed by the number of hospitalisations, a figure which has shown a downwards trajectory in recent days. However, scientific experts have warned that it is too soon to consider lifting all the measures due to fears of a “second wave” of infections.