By David Brunnstrom

Nov 27 (Reuters) - Russia's deputy U.N. ambassador said on Wednesday any decision by President-elect Donald Trump's incoming administration to cut support for Ukraine would be a "death sentence" for the Ukrainian army, while accusing Kyiv of trying to drag NATO countries into direct conflict with Russia in the meantime.

Speaking to the U.N. Security Council, Dmitry Polyanskiy accused the outgoing Biden administration of trying through its increased support to Ukraine to create a "mess, both in Russia and with the new team in the White House."

Polyanskiy said Ukrainian President Volodymyr Zelenskiy was terrified of the return of Trump in January, and had reason to be so.

"Even if we're to lay to one side the prediction that Donald Trump will cut assistance to Ukraine, which for the Ukrainian army would essentially be a death sentence, it is becoming clearer that he and his team will, in any case, conduct an audit of the assistance provided to Kyiv," he said.

Trump's transition team did not immediately respond to a request for comment on Polyanskiy's remarks.

Three sources with knowledge of the matter told Reuters earlier that Trump is considering Keith Kellogg, a retired lieutenant general who has presented him with a plan to end the Ukraine war, as a special envoy for the conflict.

Kellogg's plan for ending the war, which began when Russia invaded Ukrainian sovereign territory, involves freezing battle lines at their current locations and forcing Kyiv and Moscow to the negotiating table, Reuters reported in June.

Polyanskiy said Russia had repeatedly offered to negotiate but Ukraine and its Western backers have favored escalation.

He warned the decision by the Biden administration and its European allies to authorize the Ukrainian army to use long-range missiles far inside Russia had "placed the world on the brink of a global nuclear conflict."

"Every wave of escalation from the West is going to be decisively responded to," he said. "I will be frank, we believe that it is our right to use our weapons against the military facilities of those countries who allow the use of weapons against our facilities."

Speaking earlier at the same U.N. session, U.N. Assistant Secretary-General Miroslav Jenca highlighted recent Russian long-range missile strikes in Ukraine and called the use of ballistic missiles and related threats there "a very dangerous, escalatory development."

U.S. Deputy U.N. Ambassador Robert Wood told the session Washington would "continue to surge security assistance to Ukraine to strengthen its capabilities, including air defense, and put Ukraine in the best possible position on the battlefield."

(Reporting by David Brunnstrom; Editing by Rod Nickel)

((david.brunnstrom@thomsonreuters.com; +1 202-843-6366; @davidbrunnstrom;))