The force said its officers deployed to Shoreditch to carry out the swabs and "ensure the night time economy is a safe place for all".

A clip, posted to its Twitter page, shows police swabbing people's hands and searching a man whose face is blurred out.

No more context has been provided, leading to a deluge of tweets asking what laws allowed them to go around swabbing people, whether they had gained permission first and how they decided to test certain people for drugs.

The 31-second clip was first posted on the afternoon of January 2. It has since garnered 1.1m views.

The tweet accompanying the footage, which is set to dance music, said: "Taskforce Officers were out recently doing drug swabs in Shoreditch as part of a wider operation to ensure the night time economy is a safe place for all."

Media law trainer, author and journalist David Banks replied: "A lot of people are asking under what legal power you were doing this. Can you explain?"

Others compared the operation to the Met's refusal to investigate alleged Covid rule breaches at Downing Street, having said it has a policy of not looking into historic claims, but would investigate if presented with evidence of law-breaking.

Another Twitter user branded it a "really poor use of police resources" while others compared it to reports of drug traces found in the Houses of Parliament.

LBC has contacted the Met to provide an explanation for the video.

LBC's Matthew Thompson said: "It is also increasingly unclear under exactly what legal power police feel able to do this.

"There doesn't appear to be legal authority for random, enforced drug tests in the street. If indeed that is what is going on here."