Russia risks losing G8 membership over Crimea: US

US Secretary of State John Kerry bluntly warned Russia on Sunday that it risked losing its place among the prestigious Group of 8 developed nations over its deployment of troops in Crimea.

Kerry warned President Vladimir Putin that "he is not going have a Sochi G8, he may not even remain in the G8 if this continues. He may find himself with asset freezes, on Russian business, American business may pull back, there may be a further tumble of the rubble."

"There is a huge price to pay. The United States is united, Russia is isolated. That is not a position of strength," the top US diplomat told NBC's Meet the Press.

The United States, Britain, and France have already pulled out of preparatory meetings this week for the G8 summit due to be held in June in Sochi, amid growing global concerns over Moscow's threat to invade neighbouring Ukraine.

Ukraine's new interim government has called up all military reservists to stave off the threat and warned their country was on the brink of disaster.

"If Russia wants to be a G8 country, it needs to behave like a G8 country," Kerry also said on CBS's "Face the Nation" as he hit the Sunday morning talk shows, to ratchet up the pressure on Moscow.

And he warned: "The G8 plus some others and all of them, every single one of them, are prepared to go to the hilt in order to isolate Russia with respect to this invasion."

"They're prepared to put sanctions in place, they're prepared to isolate Russia economically, the rubble is already going down."