Republican protesters have been arrested just hours before the coronation, after police seized lock-on devices.
Footage on Twitter showed officers using their powers under the new Public Order Act, as chief executive of anti-monarchy group Republic, Graham Smith, was among those apprehended in St Martin’s Lane near Trafalgar Square.
Pictures showed demonstrators in yellow “Not My King” T-shirts, including Mr Smith, having their details taken.
In one video an officer said: “I’m not going to get into a conversation about that, they are under arrest, end of.”
The Metropolitan Police confirmed four people were arrested on suspicion of conspiracy to cause a public nuisance on St Martin’s Lane and that lock-on devices were seized.
The force also said they made a number of breaching-the-peace arrests in the area of Carlton House Terrace and a further three arrests in the Wellington Arch area on suspicion of possessing articles to cause criminal damage.
Just Stop Oil told the PA news agency approximately 13 protesters were arrested on the Mall ahead of the coronation.
A spokeswoman for the campaign group said five demonstrators were also arrested at Downing Street and one at Piccadilly.
Footage from the Mall showed the Just Stop Oil protesters being handcuffed and taken away by a heavy police presence.
Campaign group Human Rights Watch described the arrests as “incredibly alarming”, adding: “This is something you would expect to see in Moscow not London.”
One Just Stop Oil protester Ben Larsen, 25, said he was there to see the coronation and peacefully protest
Grinning at police officers, he told them: “You’ve searched me and haven’t found shit.”
A police officer told him: “You need to educate yourself on what peaceful protest is.”
On Wednesday the Metropolitan Police said they would have an “extremely low threshold” for protests during the coronation celebrations, and that demonstrators could expect “swift action”.
Under the controversial new Public Order Act, protesters who have an object with the intention of using it to “lock on” are liable to a fine, with those who block roads facing 12 months in prison.
Critics previously hit out at plans from the Met to use facial recognition software on crowds to assist their policing operations.
An official letter warning of the new powers was sent to Republic, which said its campaign around the coronation would proceed as planned.
Just after 7.30am on Saturday, one woman in a Republic T-shirt was carried away by officers during an interview with the PA news agency.
Before being arrested, she said: “We had a delivery of placards ready for the protest and then the tactical support unit questioned us as to how we we had got through the road closures.
“They questioned whether what we were doing was a delivery.
“They then said they found evidence of means of locking on, of items that could be used to lock on, and they arrested us.”
Officers carried her away from where she had been standing outside a Tesco store.
Two men who appeared to have been part of the same demonstration were carried away by officers into a marked police van.
After the apparent arrests, Republic activist Luke Whiting, 26, told PA: “Six Republic members have been arrested including the CEO as the demonstration was starting at the edge of Trafalgar Square.
“It is unclear why, potentially it is because one of them was carrying a megaphone.
“It is unclear exactly whether the police are using these new powers and whether they are misusing them to stop protest happening.”
The policing operation will see 11,500 police on duty on Saturday.
Related: Head of UK anti-monarchy group Republic arrested ahead of coronation