The campaign group Defend Our Juries, which organised the protest, said 1,500 people took part, holding signs with the messages"Oppose genocide, Support Palestine Action".

Minutes after the protest began, police began arresting demonstrators, while bystanders chanted"Shame on you" and "Metropolitan Police, choose a side: justice or genocide."

"Expressing support for a banned organisation is an offence under the Terrorism Act," the Metropolitan Police said on social media."Wherever our officers find such offences, they will make arrests."

More than 700 people were arrested at previous protests, and 138 were charged under the Terrorism Act.

Mike Higgins, 62, who is blind and a wheelchair user, was arrested last month but returned to protest on Saturday.

"I'm a terrorist too? That's the joke of the situation," he said."I've been arrested before under the Terrorism Act and I suspect I'll be again today."

The government banned Palestine Action in July after activists broke into a Royal Air Force base and vandalized planes to protest what they called Britain's support for Israel's offensive against Hamas in the Gaza Strip. The activists sprayed red paint into the engines of two tanker planes and caused further damage using crowbars.