WASHINGTON, Feb 22 (Reuters) - Western nations on Tuesday punished Russia with new sanctions for ordering troops into separatist regions of eastern Ukraine and threatened to go further if Moscow launched an all-out invasion of its neighbour.

The United States, the European Union and Britain announced plans to target banks and elites while Germany halted a major gas pipeline project from Russia, which they say has amassed more than 150,000 troops near Ukraine's borders. Moscow has denied planning an invasion.

One of the worst security crises in Europe in decades is unfolding as Russian President Vladimir Putin ordered soldiers into Donetsk and Luhansk to "keep the peace." Washington has dismissed that as "nonsense".

Satellite imagery over the past 24 hours shows several new troop and equipment deployments in western Russia and more than 100 vehicles at a small airfield in southern Belarus, which borders Ukraine, according to U.S. firm Maxar.

Weeks of intense diplomacy have so far failed and on Tuesday both U.S. Secretary of State Antony Blinken and French foreign minister Jean-Yves Le Drian cancelled separate meetings scheduled with Russian counterpart Sergei Lavrov.

"To put it simply Russia just announced that it is carving out a big chunk of Ukraine," Biden said on Tuesday.

"This is the beginning of a Russian invasion."

Plans announced by Biden to bolster Estonia, Latvia and Lithuania include sending 800 infantry soldiers and up to eight F-35 fighter jets to locations along NATO's eastern flank, a U.S. official said, but are a redistribution, not additions.

Putin did not watch Biden's speech and Russia will first look at what the United States has outlined before responding, according to Kremlin spokesperson Dmitry Peskov, cited by Russian news agencies.

Early on Wednesday, Putin said he was always open to finding diplomatic solutions but that "the interests of Russia and the security of our citizens are unconditional for us."

Moscow is calling for security guarantees, including a promise that Ukraine will never join NATO, while the U.S. and its allies offer Putin confidence-building and arms control steps to defuse the stand-off.

A meeting between Biden and Putin, brokered by France, "certainly is not in the plans" at this point in time, the White House said on Tuesday.