Boris Johnson is under growing pressure to stop non-essential construction workers heading to building sites as the country attempts to tackle the spread of coronavirus.
The Prime Minister has faced calls from across the political spectrum for more stringent rules so workers are not placed at risk, and public transport is not overwhelmed.
In an address to the nation on Monday, Mr Johnson told people not to leave their homes and go to work unless "absolutely necessary".
Stopping non-essential construction would still see building work on new hospitals take place, but would halt the building of new homes.
Asked at PMQs by Labour leader Jeremy Corbyn why construction sites had not yet been closed, Mr Johnson said: "Everybody should work at home unless they must go to work.
"If a construction company is continuing, then they must do so in accordance with advice from Public Health England.
Earlier on Wednesday, Housing, Communities and Local Government Secretary Robert Jenrick said work on building sites can continue but workers should practise social distancing.
On Tuesday, Downing Street said that construction work should continue if it can be done following Public Health England (PHE) and industry guidance.
A day later, Mr Jenrick told ITV News: "If your employer thinks they cannot follow those guidelines then they should not be operating just as they shouldn’t be breaching any other form of health and safety guidance or regulation.
"So there’s an important duty on employers to consider whether they can operate within those guidelines and if they can't then unfortunately they are going to have to temporarily close."
Shadow Secretary of State for International Trade Barry Gardiner called for construction workers to be supported with "at least the living wage" when not working.
He told ITV News: "People need to know that they are going to have - at minimum - a living wage, then they know they can do the right things by themselves and the right thing by the wider public.
"But you cannot self-isolate on a building site, you cannot self-isolate and observe the social distancing measures if you are on a building site or a hairdresser or the many, many self employed professions."
In footage filmed over London on Tuesday morning, many construction workers could be seen at work
On Tuesday, Health Secretary Matt Hancock said those who cannot work from home, including key workers in the NHS and social care, should go to work “to keep the country running”.
The Health Secretary said construction workers were among those who could continue to work as long as they could remain two metres apart at all times.
But some builders and construction workers have said they feel “angry and unprotected” going to work, while others are under pressure from employers to go in.
London Mayor Sadiq Khan’s office said the Government must act urgently to get more people staying at home following construction workers reporting to building sites and images of packed Tube trains appearing on social media.
It comes as housebuilder Taylor Wimpey said on Tuesday that it has closed its construction sites, show homes and sale sites due to coronavirus.
Transport for London (TfL) has also said work on its Crossrail sites was being temporarily suspended - but that essential maintenance of the transport network will continue.
Conservative former cabinet minister Sir Iain Duncan Smith added his voice to the calls for non-essential building work to be stopped, telling BBC Two’s Newsnight: “I think the balance is where we should delete some of those construction workers from going to work and focus only on the emergency requirements.”
Andy Burnham, mayor of Greater Manchester, told the programme: “This decision about allowing non-essential work appears to be taken for economic reasons when actually – when you’re in the middle of a global pandemic – health reasons alone really should be guiding all decision making.”
One of the reasons construction workers are still attending building sites is because they are self-employed.
The Government is also under intense pressure to set out a financial support package for self-employed workers – measures senior Conservative MP Sir Iain said were soon to be announced.
“I believe the Government has reached a conclusion about that, the best way to do it is to look back over the average for the year but that does leave out some who haven’t been self-employed for over a year,” he told Newsnight.
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