Britain’s electronic spy agency gathered emails of reporters from top U.S. and British media organizations in November 2008 in an apparent effort to test a new data-mining tool, the Guardian reported.

The communications were among 70,000 emails siphoned up in less than 10 minutes and included communications from The Washington Post, The New York Times, the Guardian, the BBC, Reuters, Le Monde and NBC, the newspaper reported, citing analysis of documents released by former intelligence contractor Edward Snowden.

The emails were saved by GCHQ – the British equivalent of the National Security Agency – and shared on the agency’s intranet as part of a test exercise, the Guardian reported. GCHQ apparently obtained the data from one of its many taps on the fiber-optic cables that comprise the backbone of the Internet.

The disclosure comes as the United States and Britain face pressure to limit government snooping into the confidential communications of reporters. In Washington, Attorney General Eric Holder recently announced tighter guidelines for the use of subpoenas, court orders and search warrants to obtain information and records of journalists.

In Britain, senior editors and lawyers have called for the introduction of a freedom of expression law in response to growing concerns about police abuse of surveillance powers linked to Britain’s Regulation of Investigatory Powers Act.

The communications gathered by GCHQ were sometimes innocuous mass emails sent to dozens of journalists by public relations firms, but also included correspondence between reporters and editors discussing stories.

There is nothing to indicate whether the journalists were intentionally targeted, the Guardian reported.

The email collection apparently was part of the testing of a tool to strip irrelevant data out of the agency’s automated collection process, the newspaper reported.

More than 100 editors in Britain have signed a letter to Prime Minister David Cameron protesting recent cases of warrantless surveillance of journalists’ communications.

In the United States, news media and press freedom advocates were outraged two years ago over disclosures that Justice Department officials obtained records from more than 20 phone lines assigned to the Associated Press and its journalists as part of a leak investigation of a failed al-Qaida plot. In a second leak investigation, a Fox News reporter was called a possible “co-conspirator” in a crime to obtain a search warrant for his records.

Under the new guidelines, federal investigators will need authorization from the attorney general if they want to seek information from journalists who used classified material or confidential sources. Previously, the department had insisted that that policy apply only to “ordinary newsgathering.”

The revelation comes in the wake of terrorist attacks in Paris on a satirical magazine, Charlie Hebdo, and on other targets that claimed 17 lives.