LIVERPOOL, Dec 13 (Reuters) - Russia faces massive consequences and severe costs if President Vladimir Putin attacks Ukraine, the Group of Seven warned in a statement on Sunday (Dec 12).

US intelligence assesses that Russia could be planning a multi-front offensive on Ukraine as early as next year, involving up to 175,000 troops.

The Kremlin denies it plans to invade and says the West is gripped by Russophobia. Moscow says the expansion of NATO threatens Russia and has contravened assurances given to it as the Soviet Union collapsed in 1991.

At a meeting in the northern English city of Liverpool, the G7 delegates said they were united in their condemnation of Russia's military build-up near Ukraine and they called on Moscow to de-escalate.

"Russia should be in no doubt that further military aggression against Ukraine would have massive consequences and severe cost in response," said the statement, which confirmed a draft version first reported by Reuters.

"We reaffirm our unwavering commitment to Ukraine's sovereignty and territorial integrity, as well as the right of any sovereign state to determine its own future."

A statement released by the Russian Embassy in London on Saturday evening, before the joint G7 document was reported, said that Britain's frequent use of the phrase "Russian aggression" during the Liverpool meeting was misleading and designed to create a cause for the G7 to rally round.

"Russia has made numerous offers to NATO on ways to decrease tensions. The G7 forum could be an opportunity to discuss them, but so far we hear nothing but aggressive slogans," the embassy statement said.