British and U.S. intelligence agencies spied on leaders during the G20 summit in 2009 in London, including then-President Dmitry Medvedev, a news report said Monday.
Emails and telephone calls from foreign politicians, especially those from Russia, Turkey and South Africa, were monitored by GCHQ and NSA in April and September 2009, the Guardian newspaper reported, citing documents revealed by NSA whistleblower Edward Snowden.
"Some delegates were tricked into using internet cafes that had been set up by British intelligence agencies to read their email traffic," the newspaper added.
Intercept specialists from the National Security Agency attempted to intercept Dmitry Medvedev's phone calls to Moscow, but it is not known whether their attempts were successful, Interfax reported.
The espionage was reportedly conducted under orders from the then-British Prime Minister Gordon Brown with the tapped information sent directly to his ministers, the report said.
The illegal surveillance reports may spark tensions amid the G8 summit, being held in Northern Ireland's County Fermanagh on Monday and Tuesday, the Guardian said.
Last week Dmitry Peskov, President Vladimir Putin's spokesman, said that Russia would consider granting asylum to Snowden, who fled to Hong Kong after revealing broad monitoring of phone call and Internet data by the NSA, if he asked for it.