The UK government's terrorism watchdog is to investigate the arrests of six men in London questioned by police over an alleged plot to attack the Pope, the British Home Secretary has confirmed.
Theresa May announced the review as she named David Anderson QC, a specialist in European Union and Public Law and human rights, as the new independent reviewer of terrorism legislation.
He will take up the role early in the new year after the incumbent, Lord Carlile of Berriew QC, conducts a "brief review" of the terror arrests during Pope Benedict XVI's visit in September.
He will examine whether the Metropolitan Police's counter-terrorism officers were justified in detaining the men in armed raids. They were all later released without charge.
Police searched eight homes in north and east London and two business premises in central London, including a street cleaning depot, as part of the investigation.
Searches of the premises did not disclose any weapons or suspicious materials, Scotland Yard said.
Reports at the time suggested the men, aged 26, 27, 29, 36, 40 and 50, had simply been overheard sharing a joke in their canteen. One of the men, 29, was arrested at a home in north London shortly before 2pm on Friday September 17.
The five other men, believed to be street cleaners, were arrested at gunpoint as armed officers swooped on their base as they prepared to start their shift shortly before 6am on the same day.
They worked for Veolia Environmental Services, a contractor which employs 650 on-street staff to keep the streets of Westminster clean.
In a written ministerial statement, Mrs May said Lord Carlile will "conduct a brief review of the arrests (and subsequent release) of six individuals under the Terrorism Act 2000 during the recent State visit to the United Kingdom by the Pope".
Mrs May said Lord Carlile had performed his role "with distinction".
Shami Chakrabarti, director of human rights group Liberty, said Mr Anderson was "a first-rate lawyer" who was widely respected in both the security and legal communities.
"His forensic skill may help build the kind of public confidence that this important non-political role has lacked for some years," she said.
"Exceptional anti-terror laws should trouble every democrat in this country. The statutory reviewer should give anxious scrutiny to their operation, not lobby for their extension."