Four people were arrested on suspicion of terrorism offences during a pro-Palestine protest in Liverpool city centre on Sunday afternoon, police said.
Merseyside police said material in support of campaign group Palestine Action was reportedly seen in the possession of a small number of protesters at the regular march for Liverpool Friends of Palestine.
More than 100 people were arrested across the country during weekend demonstrations protesting against the proscription of Palestine Action, which was banned as a terrorist organisation in June.
Police said four people from Merseyside – a 74-year-old woman from Kensington, a 65-year-old man from Brighton-le-Sands, a 28-year-old man from Garston and a 72-year-old man from Mossley Hill – were arrested on suspicion of wearing or carrying an article supporting a proscribed organisation.
All had been taken to police stations for questioning
Protests were held in Bristol, Edinburgh, London, Manchester and Truro on Saturday as part of a campaign coordinated by Defend Our Juries, a pressure group.
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.
Greater Manchester police said it had arrested 16 people on Saturday on suspicion of support of a proscribed organisation, adding that they remained in custody for questioning.
Eight people were arrested near Truro Cathedral in Cornwall after protesters gathered to show support for Palestine Action.
Avon and Somerset police said 17 people were arrested during a protest in Bristol.
Palestine Action was banned after two Voyager aircraft were damaged at RAF Brize Norton in Oxfordshire on 20 June, an incident claimed by the direct action group which police said caused about £7m worth of damage.
The home secretary, Yvette Cooper, announced plans to proscribe Palestine Action three days later, saying the vandalism of the planes was “disgraceful” and that the group had a “long history of unacceptable criminal damage”.
The ban means that membership of, or support for, Palestine Action is now a criminal offence punishable by up to 14 years in prison, under the Terrorism Act.