The British Government Communications Headquarters (GCHQ) conducted a test exercise in 2008 that intercepted the emails of journalists and editors from the U.S. and U.K.’s largest media organizations, a report said Monday, citing documents recently leaked by National Security Agency whistleblower Edward Snowden.

According to the report, emails from media organizations including BBC, Reuters, the Guardian, the New York Times, Le Monde, Sun, NBC and the Washington Post were saved and shared on GCHQ’s internal servers. The British intelligence organization was tapping fiber-optic cables in November 2008 when it captured 70,000 emails, including the ones exchanged by journalists from these media outlets, the Guardian reported, adding that the emails were intercepted in less than 10 minutes.

“Journalists and reporters representing all types of news media represent a potential threat to security,” according to one of the documents revealed by Snowden. “Investigative journalists” who specialize in defense-related exposes are a specific concern for GCHQ, the document added.

The intercepted communications, which were made available to all staff with the appropriate security clearance within GCHQ, include both simple public relations emails as well as confidential correspondence between reporters and editors discussing news articles. However, it is still unclear whether the journalists were targeted intentionally.

Last week, British Prime Minister David Cameron said that encrypted messages that cannot be intercepted by British intelligence agencies should be banned, to help authorities prevent major terror attacks. Applications such as Facetime, iMessage and Snapchat are some of the tools used to send messages that are difficult for security organizations to intercept, United Press International reported.

The latest revelation follows another disclosure by Snowden last week, claiming that Chinese spies had stolen 50 terabytes of data related to Lockheed Martin's F-35 Joint Strike Fighter jet. However, China dismissed the allegations as “groundless.”