The proscription of Palestine Action must be "withdrawn", Green Party leader Zack Polanski has said.
Addressing his party's conference in Bournemouth, Mr Polanski said the Labour government had overseen a "draconian crackdown on the right to protest" by legally banning and labelling the group a terrorist organisation.
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It comes as a group that supports Palestine Action was criticised for planning a march in London on Saturday, days after the attack on a synagogue in Manchester that resulted in the death of two men.
The Met Police has called for a planned protest, organised by Defend Our Juries, to be delayed or cancelled after the incident on Thursday, while Shabana Mahmood, the home secretary, called a separate protest