North Wales Police has been ordered to disclose the reasons for stopping a UK lawyer who represented Hamas and seizing the contents of mobile phone to closed-door court hearing.

Justice Martin Chamberlain said that he did not accept that North Wales Police could simply assert there was a lawful basis for stopping and copying the contents of solicitor Fahad Ansari’s phone, without saying what the reason was.

But the judge refused to issue an order preventing a police-appointed independent legal counsel from rstarting a review of the contents of Fahad Ansari’s phone until Ansari could appeal to a judicial review.

The decision came after North Wales police gave an undertaking that the material would not be shared with police investigators until a decision in a further court hearing.

Solicitor Fahad Ansari, who represented Hamas in a legal challenge to overturn its status in the UK as a proscribed terrorist organisation, is seeking a judicial review after being stopped by police and his mobile phone seized.

Ansari, an Irish citizen, argues that he was unlawfully stopped, detained and questioned under Schedule 7 of the Terrorism Act after he drove off a ferry with his family at Holyhead after visiting relatives in Ireland in August.

The case is understood to be the first time police have used Schedule 7 of the Terrorism Act – which allows police to stop people without grounds for suspicion – to seize and copy the contents of a phone belonging to a solicitor in the UK.

Ansari said that his phone contained material used for work, and that accessing it would breach the legal privilege of clients dating back 15 years.

Jude Bunting KC, told a court hearing today that North Wales Police, which leads counter-terrorism policing in Wales, had failed to provide any reason for stopping Ansari and seizing his mobile phone.

He told the court that Ansari’s phone contains communications with past and current clients, witnesses and legal counsel, stored on multiple applications and cloud-based services that were protected by legal privilege.

The phone contains details of at least 3,000 contacts, voice notes, memos, case papers, search terms, and meta data, the overwhelming proportion of which is likely to be legally protected.

Bunting said that Ansari had been targeted by police to obtain and access the contents of his mobile phone. A Schedule 7 stop cannot be justified on the grounds that Ansari’s clients were of interest to the police and the security service, he said.

The barrister said that it was not reasonably practicable for an independent counsel to ‘sift’ the legally privileged material on the phone, which made up 95% to 98% of the content, from non-privileged material that police were allowed to access.

North Wales Police has refused to explain how material can be sifted, apart from simply asserting “there are adequate safeguards in place,” he said.

He said it was not practicable to identify key words to carry out searches that would identify legally privileged material.

The police had given no explanation why it was necessary to search Ansari’s mobile phone, let alone why it was necessary to search it now, Bunting told the court.

“There is a real risk that legally privileged material will be provided to the examining team. If this happens, the damage to the claimant will be irreparable,” Bunting wrote in legal submissions.

Georgina Wolfe, representing North Wales Police, said that there was no evidence to support the assertion that Ansari had been stopped and his mobile phone seized can copied, because of the clients he represented.

She argued that there was an effective long-established procedure to sift legally privileged material from seized devices, under the Schedule 7 code of practice.

The court heard that the chief constable of North Wales Police had appointed an independent KC to review material on Ansari’s phone. “The chief constable has no intention of reviewing or sharing any legally privileged material,” said Wolfe.

In written submissions, Wolfe said that if any material was found that appeared to suggest Ansari was a terrorist, or requires further action by law enforcement, that material may be lawfully shared with other law enforcement agencies.

Wolfe told the court that North Wales police accepted that Ansari acting as legal representative of Hamas would not be a proper basis for stopping him under Schedule 7.

She told the court that there was a proper reason for stopping him but she was not in  a position to share it in open court.

The judge, Justice Martin Chamberlain, said that he did not accept that the chief constable of North Wales Police “could simply assert there was a proper basis of that search without saying what the reason was”.

He rejected arguments from Bunting to allow an interim injunction to prevent the contents of the phone being examined until a judicial review could consider the lawfulness of the police decision to stop Ansari under Schedule 7.

“There was a strong public interest in allowing the chief constable to pursue an investigation into whether or not the claimant was involved in terrorism,” he said.

Wolfe had offered an undertaking that the independent counsel would not inform the chief constable, “or anybody else” of the contents of the phone.

The judge said he accepted that this would involve some loss of confidentiality for Ansari, but said there was no material risk of material from his phone being communicated to the police.

The court will make a ruling to hear an explanation from North Wales Police for the reasons for stopping Ansari in a closed hearing before a special advocate, later this month.

The judge suggested that the special advocate could make an argument for a ‘gist’ of the reasons for the stop to be made public if that was appropriate.

Speaking before the hearing, Ansari said: “Even the police agree that my phone contains sensitive, privileged information. All I am asking the court on Monday is to make sure this material stays protected until a judge rules on whether the police acted lawfully in detaining me and seizing it.”

The campaigning group, Cage, said Schedule 7 was an “exploitative power”. Head of public advocacy Anas Mustapha, said:“Courts have repeatedly failed to claw back citizens’ rights undermined by Schedule 7. In this case, with the stakes so high, the judges ought to do more to defend civil liberties and the right to practice law without state harassment.”