Boris Johnson has expressed “full confidence” in Health Secretary Matt Hancock over claims he lied about protecting care homes from Covid.
Dominic Cummings says Mr Hancock misled the PM in March 2020 by promising that all residents in England discharged from hospital would be tested.
The PM’s former aide says this led to thousands of needless deaths.
Mr Hancock has denied lying but said he had been clear that it would take time to build testing capacity.
“My recollection of events is that I committed to delivering that testing for people going from hospital into care homes when we could do it,” he told a Downing Street press conference on Thursday.
“I then went away and built the testing capacity… and then delivered on the commitment that I made.”
The BBC understands acute concern was expressed in Downing Street about what was going wrong in care homes – and what was happening with testing – in the first week of May last year.
It is understood an urgent meeting was called to get to the bottom of what was going on.
In his testimony to a select committee on Wednesday, Mr Cummings said: “We were told categorically in March that people would be tested before they went back to care homes. We only subsequently found out that that hadn’t happened.
“The government rhetoric was we put a shield around care homes – it was complete nonsense.
“Quite the opposite of putting a shield around them, we sent people with Covid back to the care homes.”
Government documents show there was no requirement to test patients being discharged from hospital into a care home until 15 April last year.
And guidance dated 2 April said people without negative Covid tests could be discharged to care homes, but recommended they isolate in their own rooms.
In total, 127,758 people have died in the UK within 28 days of a positive test for the disease, official figures show.
Of these more than 42,000 – around a third – have happened in care homes in England and Wales, according to the Office for National Statistics.
The head of the National Care Association, Nadra Ahmed, told BBC One’s Question Time the government’s claim to have put a shield around homes was “absolute rubbish”.
“There was no shield,” she added.
“I think that was an utterance that came about in a form of embarrassment, perhaps, because nothing had been done for social care.”
Labour leader Sir Keir Starmer said Mr Cummings’ testimony could not be “the last word on this”, adding: “We need to get all the available evidence. I don’t think the prime minister has made good decisions in this pandemic.”
But a Downing Street spokesperson said: “The PM has full confidence in the health secretary and will continue working with him to protect public health and save lives.”
A Public Health England report, commissioned by the Department of Health, has concluded that the evidence suggests “hospital associated seeding accounted for a small proportion of all care home outbreaks” in England.
It said that, from 30 January to 12 October last year, 43,398 residents – from 5,882 separate outbreaks – had tested positive for Covid.
Some 1.6% (97) of outbreaks were identified as stemming from hospital discharges.
A total of 806 (1.2%) care home residents with confirmed infections were associated with these outbreaks, it added.
Mr Cummings left his job as Mr Johnson’s chief adviser last autumn following a power struggle within No 10.