Downing Street has rejected as “just wrong” the suggestion by Sir Keir Starmer that plans on how to scale back the coronavirus lockdown are in limbo amid the continued absence of Boris Johnson, insisting that proposals were being worked on.

The new Labour leader raised the idea in an interview with the BBC, saying that with the prime minister still recovering from his serious bout of the virus at Chequers, his official country retreat, Dominic Raab, who is standing in, was wary of making decisions.

For the past week or so it had seemed “difficult for the government to make big decisions”, Starmer told the BBC’s Coronavirus Podcast: “I suspect, although I don’t know, that Dominic Raab is just reluctant – he probably does know that it’s time for an exit strategy – but he’s probably reluctant to sign it off without the prime minister and I think there’s a bit of that in the mix.”

Johnson’s spokesman rejected this, referring to Raab’s statement on Thursday as to the conditions that must be met to ease the lockdown, which has been extended for another three weeks.

“It’s just wrong,” the spokesman said of Starmer’s comments. “What the first secretary of state set out last night is we need to take a responsible approach. We need to ensure we need to keep the public’s minds focused on staying at home, protecting the NHS and saving lives.”

Johnson left St Thomas’ hospital in central London five days ago following treatment for coronavirus, which included 48 hours in intensive care, and has since been at Chequers. He has been walking in the grounds, and joined Thursday evening’s mass applause for NHS and care staff.

The spokesman said while Johnson had spoken once to Raab by phone, he was not receiving any official papers or talking to other world leaders: “He is continuing his recovery at Chequers, and he is not doing government work.”

Asked if the government should set out further details on how and when the lockdown could be eased, the spokesman stressed the need to continue to focus on social distancing.

“We have set out the five tests which we believe need to be met in order for us to be able to consider relaxing some of the social distancing measures that are in place,” he said.

“But we are at a critical point in our response to this pandemic and we do want people to remain focused upon that core message of needing to stay at home to reduce the transmission of this disease, and to save lives.”

A plan did exist, he insisted: “Work is taking place across different parts of Whitehall in readiness for the point where we are able to relax the social distancing measures which we have in place.”

Raab set out five conditions that would need to be met before any change in policy: allow the NHS to cope; a sustained fall in the death rate; reduced wider rates of infection; a wider rollout of testing and protective medical equipment and sufficient evidence that reducing distancing measures would not cause a new virus peak.

Johnson’s spokesman said it would be up to the government’s Sage scientific committee to advise when these points had been reached.

However, he appeared to endorse the warning earlier on Friday from Grant Shapps, the transport secretary, that people should be wary of booking summer holidays.

“While we are making progress in the fight against coronavirus, we are not able to say with certainty the point at which the social distancing measures can be relaxed,” he said, noting that travel within the UK for holidays was still not allowed..

“As of today it is a fact that both the guidelines and the official Foreign Office advice do not allow for people going on holidays,” he said.