Russian premier Vladimir Putin has been warned that nations are preparing to boycott the G8 summit he is hosting this summer and may kick the federation out of the group altogether if the crisis in Ukraine is not resolved.
Britain has joined the United States and Canada in pulling out of a round of preparatory talks due to be held in the coming days to pave the way for the gathering of leading nations in Sochi.
Foreign Secretary William Hague said he would keep under review the decision over whether senior officials attend the remaining meetings, staged once or twice a month.
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His US counterpart, John Kerry, struck a more threatening tone, warning President Putin he is "not going to have a Sochi G8" if Russia continues to escalate the tinderbox situation in the former Soviet country.
"He may not even remain in the G8 if this continues," the Secretary of State said.
Kerry said he talked to foreign ministers within the group and "every single one of them are prepared to go to the hilt in order to isolate Russia".
The Group of 8 is made up of Canada, France, Germany, Italy, Japan, Russia, the USA and the UK and its presidency rotates between the members every year.
It is billed as an opportunity for leaders to have frank and open discussions about the most pressing global issues and the nation holding the presidency speaks on its behalf.
The June summit, coming on top of the Winter Olympics, was another opportunity for President Putin to enjoy the international spotlight.
If some members stage a boycott it is thought the event could still go ahead, though Foreign Office officials pointed out the "clue is in the name" and without all eight members present it would not be a meeting of the G8.