The Liberal Democrats have called for a review of the terrorism law used to arrest hundreds of supporters of the banned group Palestine Action, warning it risked having a “chilling effect” on free speech.
Last week, the Metropolitan Police arrested more than 500 people at a demonstration backing the group, which was prohibited in July.
Earlier this week, Home Secretary Yvette Cooper said the group was “not a non-violent organisation” and that she had made the decision to ban the group based on “clear security assessments”.
Separately, the Equality and Human Rights Commission has expressed concern about policing of demonstrations relating to events in Gaza, the West Bank and Israel.
However, the commission specified that its worries were about protests “not linked to any proscribed organisation”.
Writing to the home secretary and Met Police chief Mark Rowley, commission chair Baroness Kishwer Falkner said “we are concerned that some recent responses may not strike the right balance between security and fundamental rights”.
“Heavy-handed policing or blanket approaches risk creating a chilling effect, deterring citizens from exercising their fundamental rights to freedom of expression and assembly through fear of possible consequences.”
The government banned Palestine Action after the group claimed responsibility for spraying jets at RAF Brize Norton red.
It means membership of or support for the group became a criminal offence, carrying a sentence of up to 14 years.
Earlier this year, the group won permission to challenge the ban and their case will be heard in the High Court in November.
At a rally in their support in central London, banners reading “I oppose genocide. I support Palestine Action” were held up by demonstrators, hundreds of whom were arrested.
The Met Police said it was the largest number of arrests made on a single day in the last 10 years.
Lisa Smart, the Liberal Democrats home affairs spokesperson said that while the party recognised “the serious nature of this group’s activities… we are deeply concerned about the use of terrorism powers against peaceful protesters in this context”.
Writing to the independent reviewer of terrorism legislation Jonathan Hall KC, Smart said individuals “employing violence, anti-semitic abuse or hate speech to protest should face serious consequences”.
However, she argued such actions could already be prosecuted under different laws, including the Public Order Act.
She said using the Terrorism Act to “arrest individuals exercising their right to peaceful protest this weekend sets a troubling precedent and risks having a chilling effect on both free speech and legitimate democratic dissent”.
She urged Mr Hall to review the parts of the act used to make the arrests and “consider whether the legislation requires amendment to prevent misuse in future”.
Mr Hall is separate from government but has a high degree of clearance and is given access to national security information.
Pressed on the arrests earlier this week, Yvette Cooper said Palestine Action had been “involved in violent attacks” and “major criminal damage against national security infrastructure”.
She told the : “There may be people who are objecting to proscription who don’t know the full nature of this organisation, because of court restrictions on reporting while serious prosecutions are under way.
“But it’s really important that no-one is in any doubt that this is not a non-violent organisation.”