As he tried to defend his handling of the crisis, the Prime Minister insisted the number of infections and deaths from coronavirus in care homes is now “well down”.
But Sir Keir Starmer accused the Government of being “too slow to protect people in care homes”.
He then referred to official advice in place until March 12 which said it remained “very unlikely” that people in care homes would become infected.
Mr Johnson hit back: “No, it wasn’t true that the advice said that, and actually we brought the lockdown in care homes ahead of the general lockdown.”
He added: “And a huge exercise in testing is going on – a further £600 million, I can announce today, for infection control in care homes.
“And, yes, it is absolutely true that the number of casualties has been too high, but I can tell the House, as I told (Sir Keir) last week and indeed this week, the number of outbreaks is down and the number of fatalities in care homes is now well down.”
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But the Labour leader has now written to the Prime Minister, demanding he return to the Commons to “correct the record”.
He wrote: “At this time of national crisis, it is more important than ever that Government ministers are accurate in the information they give.
“Given this, I expect you to come to the House of Commons at the earliest opportunity to correct the record and to recognise that this was official Government guidance regarding care homes.”
Responding to the Labour leader in a letter of his own, the Prime Minister said he was “disappointed” at the claims made by his opposite number.
He hit back at Sir Keir, and claimed he had “inaccurately and selectively quoted from Public Health England guidance” in the Commons.
With tensions over the exchange boiling over, Mr Johnson added in his letter: “I would remind you of the commitment you made, when you became Leader of the Opposition, to work constructively with the Government in the face of this unprecedented pandemic.
“The public expect us to work together.”
From the 6,035 deaths linked to coronavirus and registered in the week to May 1, 2,423 (40 percent) were in care homes, compared to 3,214 (53 percent) in hospitals.
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Mr Johnson replied: “I have the upmost respect for all our medical professionals who are doing an extraordinary job in very difficult circumstances but what I can tell the House is that actually the number of discharges from hospitals into care homes went down in March and April.
“And we had a system of testing people going into care homes and that testing is now being ramped up.”
The Prime Minister had earlier lashed out at Sir Keir during PMQs after the Labour leader challenged him on not publishing international comparisons on death tolls from coronavirus in Tuesday’s briefing.
The Labour leader said: “Yesterday the overall figures given at the press conference for those that had died from COVID-19 was 32,692. Each one a tragedy.
“For many weeks the UK has compared the UK number to other countries.
“Last week I showed the Prime Minister his own slide, showing the UK now has the highest death total in Europe and second highest in the world.
“A version of this slide has been shown at the No10 press conference every day since March 30. That’s seven weeks.
“Yesterday the Government stopped publishing the international comparisons and the slide is gone. Why?”