Ukraine's security and defence council on Friday imposed sanctions on the television channel linked to Yevhen Murayev, the politician named by Britain as the possible leader of a Kremlin puppet government in the event of a Russian invasion.

Russia is massing increasing numbers of troops near Ukraine and an invasion could come at any time, including during this month's Winter Games, Washington said on Friday.

Murayev, a Ukrainian former opposition lawmaker who has promoted views that closely align with Russian narratives on Ukraine, has called the British allegation "stupid" while Russia labelled it disinformation.

Murayev lost his seat at the 2019 parliamentary election but still wields influence through his political party Nashi, and the Nash TV channel that is officially owned by his father Volodymyr.

Apparently anticipating the sanctions, Murayev was addressing supporters at a protest in his native city of Kharkiv while the security council met.

The sanctions were adopted "without discussion, without evidence," he told supporters in a speech broadcast on Nash TV. "...We will fight for the channel, for ourselves, for you, for our country."

Murayev's spokeswoman did not immediately respond to a request for further comment.

Russia has denied planning any military offensive against Ukraine but has pressed the West for security guarantees, including a block on Kyiv joining the NATO alliance.

Oleksiy Danilov, the secretary of the security council, at a briefing did not specify the nature of the sanctions, including whether the Nash channel would be closed.

The security council meeting was also held in Kharkiv, an eastern industrial city near the Russian border which is seen as a possible target for a Russian attack.

Ukraine last year imposed sanctions on TV channels linked to pro-Russian opposition leader Viktor Medvedchuk, angering Moscow.

Murayev on Friday claimed without evidence that Nash TV was the only channel against any war between Russia and Ukraine. "Now they are closing the Nash TV channel, which means we are on the verge of war," he told supporters.