Miliband, asked whether NATO would go to war against Moscow if it were to attack a neighbouring country or ally again, said: "We don't want all-out war with Russia. There's no question of launching an all-out war against Russia."

NATO is committed to the principle that an attack against one or several members would be considered an attack against all, and to defending its members against aggression. Georgia is not a NATO member but it has ambitions to join.

NATO was not an 'offensive' alliance, Miliband told BBC Radio.

He said no-one ever doubted that Russia's army would defeat a much smaller Georgian military.

"The question though for Russia is whether it wants to suffer the isolation, the loss of respect and the loss of trust that comes from that," he added.

Miliband was speaking a day after he called in a speech in Ukraine for relations with Russia to be reviewed. He said Russian President Dmitry Medvedev had a responsibility not to start a new Cold War.

The foreign secretary denied that his words in Ukraine, whose ambitions to become a NATO member also anger Russia, had ratcheted up tensions between London and Moscow.

He said it was right to describe Moscow's actions in the Georgian regions of South Ossetia and Abkhazia as an "international crisis" that jeopardised a growing calm and stability across Europe since the collapse of the Soviet Union.