British and U.S. spy agencies monitored the e-mails and phone calls of foreign dignitaries at two international summits in London in 2009, the Guardian newspaper reported Monday, citing documents it received from former National Security Agency contractor Edward J. Snowden.

The disclosure follows reports in The Washington Post and the Guardian two weeks ago, also based on documents provided by Snowden, that disclosed widespread U.S. surveillance of phone and Internet use by ordinary citizens in order to detect patterns that could indicate terrorist activity.

The description of high-stakes summit espionage leaves the British government in a diplomatically awkward position, with heads of state — including President Obama — already arriving in Northern Ireland on Monday for the start of the Group of Eight summit.

The latest revelations by the Guardian focused on two London summits in 2009 hosted by then-Prime Minister Gordon Brown, at a time when nations were scrambling to win a broad deal aimed at addressing the global financial crisis.

British intelligence agents, the newspaper said, had gone as far as setting up fake Internet cafés and tapping into cellular networks of diplomats and foreign officials.

Thomas Drake was indicted under the Espionage Act for retaining classified information which he shared with a journalist. Drake ultimately didn’t serve any jail time but he says the experience changed his life forever. He offers insights on what Edward Snowden now faces. (The Fold/The Washington Post)

At least some of the documents posted on the Guardian’s Web site contained the logos of the NSA as well as Canada’s security agency, suggesting that a portion of the activities were part of joint or shared operations. The documents also indicated that the British were passed information from the NSA, which reportedly was conducting an eavesdropping operation on then-Russian President Dmitry Medvedev.

The British targeted the Turkish finance minister and as many as 15 other delegates from Turkey in an attempt to assess their position on a deal, the Guardian said. British spies also provided data to their own officials from a round-the-clock operation to assess who was calling whom at the summit.

White House officials declined to comment on the report, as did British Prime Minister David Cameron. “We never comment on security or intelligence issues and I am not about to start now,” Cameron told Britain’s Sky News. “That would be breaking something that no government has previously done.”

According to one of the briefing papers provided to the Guardian, the intent of the British spying was “to ensure that intelligence relevant to [Her Majesty’s Government’s] desired outcomes for its presidency of the G20 reaches customers at the right time and in a form which allows them to make full use of it."

Scott Wilson in Belfast, Northern Ireland contributed to this report.