British police have arrested over 50 people in central London during protests against the ban on the pro-Palestinian group, Palestine Action.

Demonstrators gathered in Parliament Square holding placards reading, “I oppose genocide, I support Palestine Action.”

The Metropolitan Police say 55 people were detained for displaying support for the group. Similar protests took place in Manchester, Edinburgh, Bristol, and Truro, with more than 70 arrests reported nationwide.

Palestine Action was banned on July 5 under Britain’s Terrorism Act, making support for the group a criminal offence.

The protests come ahead of a High Court hearing on Monday, where the group’s co-founder will challenge the ban. Organizers say 120 people have been arrested so far, calling the ban a threat to freedom of expression and activism.