By Humeyra Pamuk and Kirsty Needham
MELBOURNE (Reuters) - Russia has sent more forces to its border with Ukraine and could launch an invasion at any time, including during the Beijing Winter Olympics, U.S. Secretary of State Antony Blinken said on Friday.
He said Washington was continuing to "draw down" its embassy in Ukraine and repeated a State Department call to American citizens in Ukraine to leave the country immediately.
"Simply put, we continue to see very troubling signs of Russian escalation, including new forces arriving at the Ukrainian border," Blinken told a news conference in the Australian city of Melbourne.
"As we've said before, we're in a window when an invasion could begin at any time, and to be clear, that includes during the Olympics."
Russia, which has more than 100,000 troops near Ukraine's borders, denies Western accusations it may be planning to invade its former Soviet neighbour. The Winter Olympics are being hosted by Beijing until Feb. 20.
At the opening day of the Winter Olympics last week, China and Russia declared a "no limits" partnership, backing each other over standoffs on Ukraine and Taiwan with a promise to collaborate more against the West.
Beijing supported Russia's demand that Ukraine should not be admitted into NATO, as the Kremlin amasses 100,000 troops near its neighbour, while Moscow opposed any form of independence for Taiwan, as global powers jostle over their spheres of influence.
Russia's potential invasion of Ukraine threatened the international rules based order, Blinken said, adding that if such an action went unpunished, it could have consequences in the Indo-Pacific -- an apparent hint at the threat of a Chinese invasion of Taiwan.
"If we allow those principles to be challenged with impunity, even if it's half a world away, that will have an impact here as well. Others are watching. Others are looking at all of us to see how we respond," Blinken said.
Britain said on Thursday the "most dangerous moment" in the West's standoff with Moscow appeared imminent, as Russia held military exercises in Belarus and the Black Sea following the buildup of its forces near Ukraine.
The U.S. State Department urged Americans in Ukraine to leave immediately because of what it called increased threats of Russian military action and Blinken said Washington would continue to draw down its embassy after it had ordered the departure of family members of staff at its mission in January.
"We will continue that process and we've also been very clear that any American citizens who remain in Ukraine should leave now," Blinken said.
The United States and its allies have warned Russia of harsh sanctions if it goes ahead with an invasion of Ukraine. Moscow says the crisis is being driven by NATO and U.S. actions, and is demanding security guarantees from the West, including a promise by NATO never to admit Ukraine.
(Reporting by Humeyra Pamuk and Kirsty Needham; editing by Philippa Fletcher, Timothy Heritage, William Maclean)