Fifty-five people have been arrested at a protest in London in support of proscribed group Palestine Action.
Demonstrations were held in London, Manchester, Edinburgh, Bristol and Truro as part of a campaign coordinated by Defend Our Juries.
Protesters wrote the message "I oppose genocide I support Palestine Action" on placards before being surrounded by police officers at the Mahatma Gandhi statue in Parliament Square, London.
Officers confiscated the placards and searched the bags of those arrested, with some protesters being carried away by police while others were led away in handcuffs.
Met Police arrest 55 in London
The Metropolitan Police said 55 people were arrested in Parliament Square under Section 13 of the Terrorism Act 2000 for displaying placards in support of Palestine Action.
Separately, eight people were arrested near Truro Cathedral in Cornwall after protesters gathered to show support for Palestine Action.
Devon and Cornwall Police said in a statement that around 30 protesters were involved in the "peaceful" Defend Our Juries demonstration.
The force said: "A number of placards which were contrary to the law remained on display despite police advice.
"Eight people, two men and six women, were arrested on suspicion of offences under Section 13 of the Terrorism Act 2000. They remain in police custody."
Protesters call for Palestine Action to be de-proscribed
A woman who was detained by police in Parliament Square said: "We demand that Palestine Action is de-proscribed.
"Our government is not only arming a genocide, they are using terrorism laws to silence people who speak out.
"Palestine Action are campaigning for peace. They are dismantling weapons factories."
As he was carried away by police, a protester in London said: "Freedom of speech is dead in this country, shame on the Metropolitan Police."
A small number of counter-protesters in Parliament Square held up placards which said "there is no genocide but there are 50 hostages still captive".
High Court action next week
It comes ahead of a High Court hearing on Monday in which the co-founder of Palestine Action, Huda Ammori, will ask for the green light to challenge the Home Secretary's decision to ban the group under anti-terror laws.
The ban means that membership of, or support for, the direct action group is now a criminal offence punishable by up to 14 years in prison, under the Terrorism Act 2000.
The Metropolitan Police said 70 people were arrested at similar demonstrations in Parliament Square over the past two weekends.
The move to ban the organisation came after two Voyager aircraft were damaged at RAF Brize Norton in Oxfordshire on 20 June, an incident claimed by Palestine Action, which police said caused about €7 million worth of damage.
Home Secretary Yvette Cooper announced plans to proscribe Palestine Action three days later, saying that the vandalism of the planes was "disgraceful".
Ms Cooper added that the group had a "long history of unacceptable criminal damage".
