Amnesty International said damaging disclosures at the Investigatory Powers Tribunal on Wednesday revealed that the PSNI, the Met Police and MI5 unlawfully obtained communications data of journalist Vincent Kearney.

The state bodies illegally tracked the telephone data of Mr Kearney, formerly BBC NI’s home affairs correspondent, to uncover his sources on multiple occasions over a period of eight years up to 2014, and continued to share and retain the data in the years since.

Police and MI5 have conceded that their actions amount to a breach of Mr Kearney’s human rights under Articles 8 and 10 of the Human Rights Act 1998, though reject that damages should be paid.

Patrick Corrigan, Northern Ireland director of Amnesty International UK, said the tribunal hearing had exposed “a pattern of unlawful surveillance that strikes at the heart of press freedom”.

“Our courts have, once again, laid bare a deeply troubling pattern: covert and unlawful surveillance of journalists, coupled with a reckless disregard for press freedom by both police forces and the security service,” he said.

“The tribunal has revealed one of the most sustained campaigns of unlawful state surveillance against a journalist in the UK yet documented.

“But this is not just about one reporter. [Wednesday’s] findings point to a pattern of institutional overreach where authorities unlawfully and regularly accessed journalists’ communications data in pursuit of their sources.

“No press can remain truly free while secretly monitored by the very power it is meant to hold accountable. That is why we are asking the secretary of state to set up a public inquiry.

“Only a full independent public inquiry with the power to compel evidence can restore trust, deliver accountability and safeguard press freedom in Northern Ireland.”

He added: “We are also calling on Hilary Benn to establish a commissioner for covert law enforcement in Northern Ireland to ensure covert surveillance techniques are only used within the law.

“This was proposed by the Patten Commission into policing reform, but was never implemented by then-secretary of state Peter Mandelson. We are now seeing the consequences of that failure.”

The National Union of Journalists’ general secretary, Laura Davison, also said: “Journalists have to be free to do their work in the public interest and we need to know what’s happened here.

“We need to know whether it’s impacted other colleagues within the BBC. There has to be clear accountability and transparency in terms of what’s taken place.

“We’re calling for there to be a full public inquiry into surveillance of journalists in Northern Ireland, that has to be what comes out of this.”