Britain and the U.S. have claimed Russia is an unreliable G8 partner after Russia and China vetoed imposing further sanctions against Zimbabwe at a Security Council session in New York.

The sanctions would have led to an arms embargo and travel restrictions against top Zimbabwean officials, including President Robert Mugabe. The measures were proposed following recent election violence in Zimbabwe.

Russia says the measures would set a 'dangerous precedent' for Security Council interference in internal affairs.

Western backers claim the veto deviates from agreements made at the G8 summit earlier this week.

U.S. envoy to the UN, Zalmay Khalilzad, said Russia’s “U-turn” was both surprising and disturbing.

“Only a few days ago Russia was supportive of a G8 statement, which said ‘We express our grave concern about the situation in Zimbabwe’. The Russian performance today raises question about its reliability as a G8 partner,” he said.

On Saturday Russia's Foreign Ministry issued a statement slamming the British and U.S. accusations.

“We consider such statements absolutely unacceptable. The American and British UN representatives are, at best, totally uninformed about the G8 leaders' discussion in Toyako. At worst, they are deliberately distorting the facts. Indeed, the special statement of the G8 on Zimbabwe… does not have a single word about G8 countries supporting any steps at the UN Security Council at this stage,” said Andrey Nesterenko, Russia's Foreign Ministry spokesman.