LONDON 

Amnesty International UK has urged the Metropolitan Police against mass arresting peaceful demonstrators expressing support for the recently banned group, Palestine Action, ahead of a major protest planned in London on Saturday.

The protest organized by the activist group, Defend Our Juries, is expected to draw hundreds.

Since the group’s ban on July 5 under the Terrorism Act, more than 200 people across the UK have been arrested for displaying slogans such as "I Oppose Genocide. I Support Palestine Action."

Police have indicated they may arrest hundreds more this weekend, and prison authorities have been asked to prepare for a potential influx of detainees, after the justice ministry initiated a "capacity gold demand," according to reports.

Amnesty UK Chief Executive Sacha Deshmukh urged officers to exercise restraint and uphold international human rights law, in a letter to Metropolitan Police Commissioner Mark Rowley.

"Peaceful protesters must be free to express themselves this weekend without fear of reprisals, said Deshmukh. Arresting people on terrorism offences for peacefully holding a placard flies in the face of international human rights law."

"At a time when people are quite rightly outraged by the genocide they see being perpetrated in Gaza, it is more crucial than ever that there is space to peacefully express that outrage,” he also said.

The letter argues that criminalizing protest slogans supportive of Palestine Action breaches the UK’s international obligations to protect freedom of expression and assembly.

It adds that under international law, protest speech can only be criminalized if it incites violence, serious property damage, hatred or discrimination -- criteria which, Amnesty notes, are not met by holding a placard.

The letter also references the High Court’s recent decision to grant a full hearing to a judicial review challenge against the proscription.

The Court ruled that the case raised "serious issues to be tried," meaning the legal foundation for arrests under sections 12 and 13 of the Terrorism Act is now in doubt.

The UN High Commissioner for Human Rights also publicly criticized the UK’s decision to ban Palestine Action.

And the UN Special Rapporteur on Counter-Terrorism and Human Rights has been granted permission to intervene in the judicial review.

Defend Our Juries, which focuses on civil disobedience and protest trials, has led peaceful demonstrations in Westminster since the Palestine Action ban took effect. The protest on Saturday is expected to include up to 500 demonstrators who are expected to hold placards in open defiance of the ban.

Amnesty International has urged police to focus on facilitating peaceful protest rather than suppressing it.

"I call again on the Met police to think carefully before making rash decisions this weekend – their job is to facilitate peaceful protest, not shut it down," said Deshmukh.

In June, the government announced a ban under the Terrorism Act 2000 after activists from Palestine Action spray-painted planes at a Royal Air Force base, an act being investigated under counter-terrorism laws.

The ban was later passed in the House of Commons and the House of Lords in July.