LONDON // Documents leaked by US former spy Edward Snowden appear to show that Britain spied on foreign delegates at the 2009 London G20 meetings, a newspaper reported today.
Among the officials targeted were delegates from Nato ally Turkey and from fellow Commonwealth state South Africa, said The Guardian.
Britain used "ground-breaking intelligence capabilities" to monitor communications between officials at the two meetings in April and September of 2009, the daily reported.
The revelations are likely to be an embarrassment to Britain, which is hosting the two-day G8 summit in Northern Ireland from Monday — the biggest gathering of international leaders since the G20 four years ago.
British prime minister David Cameron refused to comment on the report.
Asked whether he could guarantee his guests that no similar operation was in place as they gathered at the luxury Lough Erne resort, Mr Cameron would not be drawn.
"We never comment on security or intelligence issues and I am not about to start now," he told Sky News television.
"I don't make comments on security or intelligence issues — that would be breaking something that no government has previously done."
Leaders from the Group of Eight industrialised powers — Britain, Canada, France, Germany, Italy, Japan, Russia and the United States — are meeting at the Lough Erne luxury resort for talks set to be dominated by the Syrian conflict, tax transparency and free trade.
The Guardian cited documents it had seen concerning the work of Britain's Government Communications Headquarters (GCHQ), its electronic eavesdropping agency.
According to the files, British spies tricked delegates into using specially prepared internet cafes. Those cafes allowed the spies to intercept communications and monitor email messages and phone calls through delegates' BlackBerry devices.
GCHQ was also able to track when delegates were contacting each other and the agency targeted certain officials, including the Turkish finance minister, according to documents shown to the newspaper.
They also singled out South African computers for special attention, according to one document.
They were said to have enabled a team of 45 analysts to be provided with live round-the-clock summaries of who was phoning whom during the proceedings.
The Guardian also said that GCHQ received reports from a US National Security Agency (NSA) attempt to listen in as Dmitry Medvedev, then the Russian president, made a call via satellite to Moscow.
The documents suggest that orders to gather intelligence on delegates came from a senior level within the government of Britain's then prime minister Gordon Brown, said the newspaper.
Two documents explicitly mention information being passed on to ministers.
A briefing paper prepared for GCHQ director Iain Lobban, dated January 9, 2009, set out the government's priorities for the April G20 leaders' summit.
"The GCHQ intent is 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," it noted.
A week after the September summit of finance ministers, an internal review concluded: "The call records activity pilot was very successful and was well received as a current indicator of delegate activity.
"It proved useful to note which national delegation was active during the moments before, during and after the summit. All in all, a very successful weekend with the delegation telephony plot."
Mr Snowden is hiding in Hong Kong and the United States has launched a criminal investigation after the former CIA technical assistant blew the lid on the NSA's vast electronic surveillance operation.
The Guardian and The Washington Post earlier this month published leaked information from the 29-year-old intelligence technician that revealed the existence of a top-secret NSA programme to collect and analyse data from internet users around the world.