Republican protesters appear to have been arrested ahead of the King’s Coronation.

On Saturday morning, footage shared on Twitter appeared to show Graham Smith, chief executive of the anti-monarchy group Republic, being apprehended by police in St Martin’s Lane, Westminster.

Pictures seemed to show demonstrators in yellow “Not My King” T-shirts, including Mr Smith, having their details taken by officers.

Protesters thought to have been arrested

In one video, an officer says: “I’m not going to get into a conversation about that – they are under arrest, end of.”

The Metropolitan Police announced on Wednesday that they would have an “extremely low threshold” for protests during the coronation celebrations, and that demonstrators could expect “swift action”.

After the apparent arrests, Republic activist Luke Whiting, 26, told the PA news agency: “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.”

One woman in a Republic T-shirt who was arrested told PA: “We had a delivery of placards ready for the protest and then the tactical support unit questioned us as to how 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.”

She was carried away by officers 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.

Met Police issues statement

In a statement on Twitter, the Metropolitan Police said: “A significant police operation is under way in central London.

“We have made a number of arrests in the area of Carlton House Terrace.

“The individuals have been held on suspicion of breaching the peace.

“Earlier today we arrested four people in the area of St Martin’s Lane.

“They were held on suspicion of conspiracy to cause public nuisance.

“We seized lock-on devices.

“A further three people were arrested in the area of Wellington Arch.

“They were held on suspicion of possessing articles to cause criminal damage.

“There will be further updates later today.”

On Saturday, the policing operation is set to see 11,500 police officers on duty.