Speaking at a news conference, Zelensky said the coup was being planned for December 1 or 2, and there is audio of Ukrainian and Russian plotters discussing the plan.

The Kremlin rejected Zelensky's claim that Russia is involved in plotting a coup in Ukraine. "Russia never had any plans to take part. In general, Russia is never engaged in that kind of thing," Kremlin spokesperson Dmitry Peskov said on a conference call with journalists Friday.

For weeks, Western officials have been expressing growing concern about Moscow's military activity on the Ukrainian border -- with the US considering sanctions if Russia invades Ukraine.

"We don't know what President [Vladimir] Putin's intentions are, but we do know what's happened in the past," US Secretary of State Anthony Blinken said during a trip to Senegal last week, referring to Russian military incursions, acknowledged or not, into neighboring countries.

The head of Ukraine's Defense Intelligence Agency, Brigader General Kyrylo Budanov, told the US defense newspaper Military Times that Russia was increasing troop levels and weapons systems in Crimea for an offensive that could come at any time.

The Kremlin has repeatedly said Russia has no plans to invade Kremlin, accusing Western countries of "hysteria."