Irish novelist Sally Rooney has told the High Court that the ban on Palestine Action could force her to withdraw her books from sale in the UK because the terrorism designation may make it illegal for her to receive royalties.

Rooney said the proscription means that any royalties she receives from publishers or production companies could be interpreted as a criminal offence.

The group was banned in July after the home secretary accused it of causing serious property damage.

In an Irish Times article in August, Rooney said she intended to use her royalties “to go on supporting Palestine Action.”

In witness statements submitted to the court, Rooney said she believes Israel has committed genocide in Gaza, and argued that Palestine Action’s activities sit within a “long and proud tradition of civil disobedience – the deliberate breaking of laws as an act of protest.”

She added: “I myself have publicly advocated the use of direct action, including property sabotage, in the cause of climate justice. It stands to reason that I should support the same range of tactics in the effort to prevent genocide.”

Rooney highlighted that Element Pictures, which has adapted her work, had already raised concerns that continuing to pay her could put them at legal risk.

She also said the uncertainty around whether her publisher can lawfully pay her royalties means that “my existing works may have to be withdrawn from sale” in the UK.

“The disappearance of my work from bookshops would mark a truly extreme incursion by the state into the realm of artistic expression,” she said.

UN warns UK ban is a breach of human rights

A UN official has also intervened in the case, criticising the UK’s decision to ban Palestine Action as a “fundamental breach of human rights.”

Speaking on the second day of the judicial review, barrister Adam Straw KC presented a statement from Ben Saul, the UN Special Rapporteur on Human Rights and Counter-Terrorism.

Straw said Saul’s statement was endorsed by other UN Special Rapporteurs focusing on human rights, and the proscription of groups that are not genuinely terrorist is a practice “often seen in authoritarian states.”

“It is deeply concerning that such practices appear to have spread to a number of liberal democracies,” Saul wrote in his witness statement.

“Organisations must never be listed as terrorist for engaging in protected speech or legitimate activities in defence of human rights.”

As the case opened on Wednesday, police arrested protesters opposing the ban outside the court.

Dozens gathered behind the Royal Courts of Justice, holding placards reading “I oppose genocide, I support Palestine Action.”

Lawyers representing Huda Ammori, a co-founder of the group, argued that the chilling effect of the ban was already evident, citing arrests across the country linked to demonstrations against the proscription.