Boris Johnson has backed his key adviser Dominic Cummings, amid a row over the aide’s travel during lockdown.
The PM said he believed Mr Cummings had “no alternative” but to travel from London to the North East for childcare “when both he and his wife were about to be incapacitated by coronavirus”.
“In every respect, he has acted responsibly, legally and with integrity,” Mr Johnson said.
It follows calls from several Tory MPs for Mr Cummings’ resignation.
Labour leader Sir Keir Starmer said Mr Johnson’s decision to take no action against Mr Cummings was “an insult to sacrifices made by the British people”.
Leaving Downing Street after about six hours in Number 10 on Sunday, Mr Cummings refused to answer questions.
Meanwhile, Mr Johnson said parents and teachers should prepare for the phased reopening of schools in England to start on 1 June as planned.
He also announced that a further 118 people had died with coronavirus in the UK, across all settings, bringing the total to 36,793.
On Saturday, Mr Cummings and the government had said he acted “reasonably and legally” in response to the original claims that he drove 260 miles from London to County Durham with his wife, who had coronavirus symptoms.
But, speaking at Downing Street’s daily coronavirus briefing, Mr Johnson called “some” of the claims “palpably false”.
Mr Johnson said he held “extensive” discussions on Sunday with Mr Cummings, who he said “followed the instincts of every father and every parent – and I do not mark him down for that”.
“Looking at the very severe childcare difficulties that presented themselves to Dominic Cummings and his family, I think that what they did was totally understandable – there’s actually guidance… about what you need to do about the pressures that families face when they have childcare needs.
“He found those needs where they could best be served, best be delivered and yes, that did involve travel.”
When asked whether Mr Cummings made a trip to Barnard Castle – 30 miles from Durham – during his isolation in April, Mr Johnson said his aide isolated for 14 days and he was “content that in all periods and in both sides (of isolation) he behaved responsibly and correctly”.