Moscow: Announcing a special "military operation" in the Donbas region, Russian President Vladimir Putin warned other countries that any attempt to interfere with the Russian action would lead to "consequences".

Delivering an emergency address, Putin said the operation has been launched to demilitarize Ukraine and defend people "suffering persecution and genocide" by the Kiev regime.

"I have taken the decision to carry out a special military operation. Its goal will be to defend people who for eight years are suffering persecution and genocide by the Kiev regime. For this we will aim for demilitarization and de-Nazification of Ukraine," said Putin, asking Ukrainian soldiers to lay down arms.

"Anyone who tries to interfere with us, or even more so, to create threats for our country and our people, must know that Russia's response will be immediate and will lead you to such consequences as you have never before experienced in your history," he added.

This comes hours after Ukrainian President Volodymyr Zelenskyy said Ukraine has not posed and will not pose a threat to Russia.

In an emotional appeal delivered largely in Russian, Zelenskyy said, "You are being told that Ukraine can pose a threat to Russia.

"It was not like this in the past, it is not like this now and it will not be so in the future. You demand security guarantees from NATO. We also demand guarantees of our security - from you, from Russia, and other guarantors of the Budapest memorandum," Zelenskyy said in a video address.

Ukrainian President also refuted Moscow's claims that his country poses a threat to Russia and warned that a Russian invasion would cost tens of thousands of lives.

The White House on Wednesday had warned that Putin will face significant consequences if Moscow invades Ukraine.

United Nations Secretary-General Antonio Guterres asked the Russian President to stop "attacking Ukraine" and to give peace a chance, speaking at an emergency UN Security Council meeting on Wednesday night.

"The day was full of rumours and indications of an offensive against Ukraine was imminent. In the recent past, there were several situations with similar indications, similar rumours," Guterres told the council.

"I was wrong. And I would like not to be wrong again today," he added.