Police are arresting protesters demonstrating against Palestine Action being designated as a terrorist group.
Groups gathered in central London on Saturday for the second week in a row to protest the decision ban the direct-action group.
The Metropolitan Police arrested 29 people for a similar demonstration last weekend.
Two small groups sat at the steps of both the Mahatma Gandhi and Nelson Mandela statues shortly after 1pm in Parliament Square for the demonstration, organised by campaign group Defend Our Juries, and received a brief round of applause.
The individuals then wrote the message “I oppose genocide, I support Palestine Action” with black markers on pieces of cardboard, and silently held the signs aloft, surrounded by Metropolitan Police officers, who formed a cordon around the Gandhi statue.
By 1.20pm, the force confirmed they were “in the process of making arrests”. It is not yet known how many are being detained.
Officers could be seen searching the bags of protesters and taking their ID cards. Some demonstrators could be seen lying on top of each other while police held their handmade signs.
The protesters were then led away from the statues by officers into waiting police vans parked around the square.
More demonstrations will take place in London, as well as in Manchester, Cardiff and Londonderry, Northern Ireland, on Saturday, the campaign group said.
Before the protest, Scotland Yard said that officers will act where criminal offences, including support of proscribed groups or organisations, are committed.
The force added that this includes “chanting, wearing clothing or displaying articles such as flags, signs or logos”.
The terror group designation means that membership of, or support for, Palestine Action is a criminal offence punishable by up to 14 years in prison.
The move to ban the organisation came after two Voyager aircraft were damaged at RAF Brize Norton in Oxfordshire on 20 June in an incident claimed by Palestine Action which caused an estimated £7 million worth of damage.
Home secretary Yvette Cooper announced plans to proscribe Palestine Action, saying that the vandalism of the planes was “disgraceful” and the group had a “long history of unacceptable criminal damage”.
