The Russian delegation to the G8 summit in Northern Ireland in June will be based in the Irish Republic – prompting speculation that it fears eavesdropping by the UK authorities.
The Russians, led by Vladimir Putin, and part of the huge US delegation to the conference at the Lough Erne Golf Resort will be staying south of the border.
The Cold War may be over, but a diplomatic source conceded that the conference, which is being arranged by the Foreign Office, comes at a time of considerable diplomatic tension between Britain and Russia.
Many in the US delegation will be staying in Co Cavan's Slieve Russell Hotel.
It is a luxury 222-bedroom venue set in a 300-acre estate, just 40 minutes' drive from the Lough Erne resort.
It is believed the entire Russian contingent will be staying in Sligo, where the Clarion Hotel and Spa is block-booked for 10 days from June 9.
The Clarion is a converted mental hospital which was built in 1948 and is set in large grounds.
It has 162 rooms – all of which have been booked for the Russian contingent.
The diplomatic source pointed out that journey times to the Lough Erne resort from Sligo (one hour, five minutes) or Cavan (40 minutes) are much shorter than from Belfast (one hour, 40 minutes).
He said that the long road journey had been noted by some advance parties sent by participating countries, most recently France.
When he took over as head of security service MI5 in 2007, Jonathan Evans complained he was having to devote increased resources to monitoring suspected Russian agents operating in London.
There are believed to be about 40 of them working under diplomatic cover, the same number as operated in the capital at the height of the Cold War.
Britain accused Russian agents of murdering Alexander Litvinenko, a defector who had been working for British and Spanish intelligence when he was poisoned in London in 2006.
More recently, WikiLeaks cables revealed British concerns that its embassy staff in Moscow were being hounded as spies by Russian security services.
Jonathan Powell, Tony Blair's former chief of staff, confirmed Russian claims that Britain carried out surveillance in Moscow using cameras and listening devices hidden in "plastic rocks".
Russian claims to have caught British agents retrieving information in 2006 were officially denied by the UK Government.
Only last month Britain complained that Denis Keefe, the deputy head of its Moscow Embassy, was being hounded and accused of being an MI6 agent working under diplomatic cover. The case was discussed at an Anglo-Russian meeting in London three weeks ago which was attended by William Hague, where the Litvinenko case was also on the agenda.