Mobile phone footage has emerged of Professor Chris Whitty, Chief Medical Officer for England, being manhandled by two men in the street.
The video, which appeared on Twitter, has been condemned by vaccines minister Nadhim Zahawi, who tweeted: "This is disgusting and these thugs must be found and charged.
"Zero tolerance for harassing a public servant."
The footage shows Professor Whitty struggling to free himself from the men's grasp as they cling on to him, laughing and posing for the camera.
Prof Whitty manages to walk a few steps away, but the men hold onto him again as he crosses a road.
Eventually, a voice - thought to be from a passer-by - can be heard telling the men to "leave this gentleman alone".
It is not clear when or where the incident took place, but Sky News has asked Downing Street for a response to the video.
It is the second time this year Prof Whitty has been harassed on camera.
In early February he was queuing at a food stall in London when a youth approached him and said: "Liar. You're a liar. Mandem, he's a liar... You're a liar. You life about the COVID-19 cases. Stop lying to the TV, man."
The scientist did not react and later told a Downing Street briefing that the "odd young lad" was "showing off".
He said he "didn't think anything of it, frankly", adding: "I'm sure he'll become a model citizen in due course and hopefully more like Captain Tom, who is the kind of person who I think much more exemplifies the spirit of the UK."
Prof Whitty, a physician and epidemiologist, has played a key role in the response to the COVID pandemic in the UK, acting as chief medical adviser to the prime minister and his team and often appearing at government news conferences.
Prof Whitty was previously chief scientific adviser at the Department of Health and worked on the Ebola outbreak of 2014.