The Met Police are shutting down an anti-coronavirus restrictions protest in London because crowds have “not complied” with social distancing rules.
Demonstrators have been asked to leave and the force said anyone who stayed could be subject to enforcement.
Thousands gathered in Trafalgar Square to protest against government rules, with very few wearing masks.
Protests are exempt from the rule-of-six restrictions, but demonstrators must social distance.
Organisers must also submit a risk assessment.
Rules in England limit indoor and outdoor gatherings to six people, with some exceptions.
In a statement, the Met said: “Crowds in Trafalgar Square have not complied with the conditions of their risk assessment and are putting people in danger of transmitting the virus.
“This has voided their risk assessment and we have informed the event organisers they are no longer exempt from the regulations.”
“By leaving now, you can keep yourself safe and avoid any enforcement action being taken by officers,” the statement added.
The force said many protesters were not maintaining social distancing, a term of the risk assessment submitted by event organisers.
Earlier, police confiscated a makeshift riot shield from one man.
The “we do not consent” rally comes a week after a separate event which saw more than a dozen officers injured when a “small minority” targeted police and more than 32 arrests were made.
Commander Ade Adelekan, who is leading the Met operation, previously said that while there was “great frustration” at the regulations, they were designed to keep people safe from the virus.
“By flagrantly gathering in large numbers and ignoring social distancing, you are putting your health and the health of your loved ones at risk,” he said.
He added that he would not tolerate police being targeted during protests and officers would “respond quickly to any scenes of violence”.