US Secretary of State Antony Blinken said Thursday that Russia is preparing to attack Ukraine "in the coming days," calling it "the most immediate threat to peace and security."

Speaking at a UN Security Council meeting on Ukraine and the Minsk agreement, the top US diplomat said Russia's claim that Moscow is drawing down its forces near Ukrainian borders is not indicated by evidence Washington is seeing.

"We do not see that happening on the ground," said Blinken. "Our information indicates clearly that these forces including ground troops, aircraft, ships, are preparing to launch an attack against Ukraine in the coming days".

He warned that the crisis directly affects every member of the Council and every country in the world.

Blinken's remarks were delivered before his trip to Germany to attend the Munich Security Conference.

US envoy to the UN Linda Thomas-Greenfield said she asked Blinken to directly address the Council and talk about "the serious situation" in Ukraine.

The secretary of state said Russia first plans to manufacture a pretext for an attack on the former Soviet republic.

"This could be a violent event that Russia will blame on Ukraine, or an outrageous accusation that Russia will level against the Ukrainian government ... It could be a fabricated so-called terrorist bombing inside Russia.

"The invented discovery of a mass grave, a staged drone strike against civilians, or a fake, even a real attack using chemical weapons,” he said. “Russia may describe this event as ethnic cleansing or a genocide, making a mockery of a concept that we in this chamber do not take lightly.”

Blinken said Moscow will then drop missiles and bombs across Ukraine and disrupt communications.

"Cyberattacks will shut down key Ukrainian institutions. After that, Russian tanks and soldiers will advance on key targets that have already been identified and mapped out in detailed plans. We believe these targets include Ukraine's capital Kyiv, a city of 2.8 million people.

"And conventional attacks are not all that Russia plans to inflict upon the people of Ukraine. We have information that indicates Russia will target specific groups of Ukrainians," he said.

"And here today, we are laying it out in great detail with a hope that by sharing what we know with the world, we can influence Russia to abandon the path of war and choose a different path," said Blinken.

The Minsk agreement remains the only framework for a peaceful settlement for the conflict in eastern Ukraine and the UN calls parties in the region to refrain from any unilateral measures that may go against the agreement.

Speaking at the same meeting, Rosemary DiCarlo, the UN's top official for political and peacebuilding affairs, said the situation in eastern Ukraine is "extremely dangerous."

Amid reports of fresh cease-fire violations across the contact line in the past several hours, DiCarlo said: "If verified, these violations must not be allowed to escalate further.

"We call on all sides to exercise maximum restraint at this time," she added.