The prime minister was asked on Tuesday whether he had stopped shaking hands with people in an effort to reduce the risk of spreading Covid-19.
He told reporters: "I am shaking hands. I was at a hospital the other night where I think there were coronavirus patients and I was shaking hands with everybody, you will be pleased to know, and I continue to shake hands.
"People must make up their own minds but I think the scientific evidence is… our judgement is that washing your hands is the crucial thing."
Angela Rayner, the favourite to win Labour’s deputy leadership contest next month, jumped on the prime minister’s comments, accusing him of lying about shaking hands with patients.
She wrote on Facebook: “Boris Johnson visited Kettering General Hospital and there are NO Coronavirus cases there, but he said he shook hands with patients who had #Coronavirus.
“Stop it now, you were absent when floods devastated communities, now daft #coronavirus stories, go back to hiding in fridges!”
A Number 10 spokesperson would not comment specifically on Angela Rayner’s comments but told Yahoo News UK: “The PM visited a hospital where there were coronavirus patients being treated and he met staff who were treating them.”
Elsewhere in the world, people are rejecting handshakes and refusing kisses in an attempt to reduce the spread of the disease.
A video has been widely shared showing people in China tapping their feet against one another – dubbed the "Wuhan Shake" – as a hands-free greeting.
Prime ministers usually have an audience with the Queen each Wednesday where they typically shake the monarch's hand.
Johnson is also due to host a reception in Downing Street later this week.
Earlier, health secretary Matt Hancock said scientific advice suggests "the impact of shaking hands is negligible and what really matters is that you wash your hands more often".