UNITED NATIONS, Feb 17 (Reuters) - U.S. Secretary of State Antony Blinken laid out at the United Nations Security Council on Thursday how Washington believes Russia could seek to invade Ukraine, warning that Moscow was preparing to attack its neighbor in the "coming days."

Blinken, as other U.S. officials have done over the past two weeks, accused Russia of planning to manufacture a pretext for an attack on Ukraine that could include "a fake, even a real, attack using chemical weapons," and said: "Russia may describe this event as ethnic cleansing or a genocide." read more

Russia's Deputy Foreign Minister Sergei Vershinin rejected Blinken's statement a "regrettable" and "dangerous" move that further fuels tensions. He said Russian forces remain on Russian territory and some units were already returning to their bases following exercises.

Blinken pushed Moscow to announce "with no qualification, equivocation or deflection" that it will not invade Ukraine.

"State it clearly. State it plainly to the world, and then demonstrate it by sending your troops, your tanks, the planes back to their barracks and hangars and sending your diplomats to the negotiating table," Blinken said.

Russia has denied it wants to invade Ukraine. The crisis, however, has prompted the U.S.-led NATO alliance to shore up its presence in member states closer to Russia or Ukraine. Ukraine is not a NATO member and Russia does not want it to be allowed to join.

Blinken made his U.N. appearance at a meeting of the 15-member council on the Minsk agreements, which aim to end an 8-year-long conflict between the Ukrainian army and Russian-backed separatists in the east of the country.

"I am here today not to start a war, but to prevent one," he said.

Tensions between Moscow and Western capitals are high following weeks of United States accusations that Russia has deployed up to 150,000 troops near Ukraine's borders for an invasion. Moscow accuses the West of hysteria.

Blinken said U.S. information indicated that Russian forces "are preparing to launch an attack against Ukraine in the coming days" and had identified main targets, including the Ukrainian capital Kyiv. Blinken said he has asked Russian Foreign Minister Sergei Lavrov to meet in Europe next week.

Britain's Minister for Europe and North America, James Cleverly, told the Security Council: "Russia has deployed the forces necessary to invade Ukraine, and now has them readied for action."