The battle lines hardened between British authorities and The Guardian newspaper over its publication of material leaked by fugitive United States intelligence contractor Edward Snowden, with Prime Minister David Cameron accusing the newspaper of damaging national security.
His assertion, made in Parliament on Wednesday, came just days after the newly appointed director of Britain's MI5 domestic security service, Andrew Parker , said that leaks about secret US and British electronic surveillance programmes had caused enormous damage and handed "the advantage to the terrorists".
The prime minister's remarks added fuel to a debate that pits the security services and the government against some lawmakers and civil liberties groups, who argue that the surveillance programmes represent an excessive and possibly unlawful breach of personal privacy.
Cameron seemed to encourage lawmakers to formally investigate whether The Guardian had erred in publishing secrets provided by Snowden, who has been given temporary sanctuary in Russia.
Hours after Cameron spoke, The Guardian reported that Parliament's Home Affairs committee would include the newspaper's actions in a broad investigation into counterterrorism. Keith Vaz, the chairman of the panel, was quoted as saying the committee would scrutinise "elements of The Guardian's involvement in, and publication of, the Snowden leaks". But he declined to say whether Alan Rusbridger, the newspaper's editor, would be called to testify.
Concerns among British civil liberties groups centre on the Government Communications Headquarters, widely known as GCHQ, the electronic eavesdropping arm of the security and intelligence services.
The confrontation between the authorities and The Guardian took bizarre turns this year when British airport authorities cited counterterrorism legislation to briefly detain David Miranda, the partner of the journalist who led The Guardian's reporting, Glenn Greenwald, as Miranda was travelling through London's Heathrow Airport.
Rusbridger disclosed that GCHQ had sent two operatives to his newspaper's offices to oversee the destruction of computer hard drives said to contain leaked information.
Rusbridger has said The Guardian told the British authorities that some of the information it received from Snowden had been sent to ProPublica, an independent, non-profit news operation, and to The New York Times. The British government asked The New York Times to relinquish the classified material, but the newspaper has said it had refused the request.
Responding to a question in Parliament on Wednesday, Cameron said: "The plain fact is that what has happened has damaged national security and in many ways The Guardian themselves admitted that when they agreed - when asked politely by my national security adviser and cabinet secretary - to destroy the files they had, they went ahead and destroyed those files.
"So they know that what they are dealing with is dangerous for national security," he said.
Asked by Liam Fox, a former defence secretary, whether there would be a "full and transparent assessment" of The Guardian's actions, Cameron said it was up to parliamentary committees to determine "if they want to examine this issue and make further recommendations".
In a telephone interview, Rusbridger said The Guardian did not accept Cameron's accusation. "We went along with the destruction of the computers in the knowledge that we could carry on reporting from New York," he said.
Rusbridger said it was ironic, at a time when the government said it backed a free press, that "not only have they tried to prevent The Guardian from reporting, but they now want newspapers to appear before Parliament to account for themselves".