Police had to deal with disorder that broke out at a St George’s Day event in Whitehall.

Mounted officers on horses had to intervene after a group broke through a police cordon formed to stop people who had moved past an area in Richmond Terrace, which was allocated for the event, the Metropolitan Police said.

The force posted on X, formerly Twitter, earlier in the day to say they expected “far-right groups and groups linked to football clubs” to attend the event.

The Metropolitan Police later shared a video on X that appears to show officers forming a cordon but a group, some waving flags and others wearing St George’s flags, pushing past it before two mounted officers on horses intervene.

The Metropolitan Police posted the video just after 2pm on Tuesday along with the message: “The event is not due to start for an hour and regrettably officers are already dealing with disorder.

“There is an area allocated for this event in Richmond Terrace. This group went past it and continued up Whitehall.

“When officers formed a cordon and asked the group to turn round, they reacted by violently forcing their way through. Mounted officers intervened with horses to restore the cordon.”

Whitehall had to close to traffic while police officers dealt with the incident.

Video footage has been posted on social media showing a man who appears to have been detained by police at the event.

Another earlier post from police said a number of people had been seen in the area wearing masks, and a Section 60AA order is in force in the boroughs of Lambeth and Westminster “giving officers the power to require the removal of face coverings”.

A Section 60 order, giving officers additional search powers, is also in force in the same area to prevent crime and disorder, the force added.

After the incident, a group gathered on Whitehall opposite Downing Street where there was also a large police presence.

Attendees waved St George’s Cross flags and listened to speeches, including by Tommy Robinson who was cleared of breaching a dispersal order at court on Tuesday.