Construction firms that have not reopened since the start of lockdown are to be encouraged to return to work, Boris Johnson has said.

In his special address to the country on Sunday evening, the prime minister said lockdown could not yet end but noted the impact of measures to limit the virus on the economy.

“We now need to stress that anyone who can’t work from home, for instance those in construction or manufacturing, should be actively encouraged to go to work,” he said. But he added that employees must be safe and people should “avoid public transport if at all possible”.

“We must and will maintain social distancing, and capacity will therefore be limited. So, work from home if you can, but you should go to work if you can’t work from home.”

Construction work has been permitted in England since the start of the lockdown and ministers have repeatedly encouraged the industry to open, although Johnson’s instruction was the most high-profile statement to date. At its highest point, some 65 per cent of UK sites by value had closed down, but last week that figure was down to 37 per cent, according to data provider Glenigan.

Johnson’s comments followed days of national newspaper speculation about the rollback of the Coronavirus Job Retention Scheme, with reports that a new announcement could take place early this week about a reduction in the amount the Treasury will pay out under the scheme.

Civil Engineering Contractors Association chief executive Alasdair Reisner said Johnson’s statement was in line with previous industry guidance.

“Companies will still need to assess whether they can operate while protecting their workforce, in line with the Site Operating Procedures and public health guidelines, which will vary for different nations. However if work is possible, industry can play an important role in rebuilding the economy post COVID-19,” he said.

Scotland’s first minister Nicola Sturgeon noted different restrictions are in place in different countries. Of Johnson’s announcement she said: “I think it is incumbent on him to stress that when he is talking about lifting these restrictions […] he is talking for England.”

Non-essential construction work remains banned in Scotland.

Labour party leader Keir Starmer said: “This statement raises more questions than it answers, and we see the prospect of England, Scotland, Wales and Northern Ireland pulling in different directions.

“The prime minister appears to be effectively telling millions of people to go back to work without a clear plan for safety or clear guidance as to how to get there without using public transport.”