Chechen leader Ramzan Kadyrov has reacted furiously to Instagram's taking down of a video he posted to the social media site, depicting Russian opposition leaders in the crosshairs of a sniper rifle.

A spokesman for Instagram said that the video violated the social media website's community guidelines, which prohibit threats,business daily Vedemosti reported.

Responding to links to Kadyrov's video now showing a message that reads: "Content unavailable", the Chechen strongman said Instagram's action was an infringement of his freedom of speech.

"As soon as I said a few words about the United States leash dogs, they immediately removed the post from Instagram," he wrote.

"That's their lauded freedom of speech, American-style. You can write whatever you want, but don't touch America's dogs, the friends of the State Department and Congress," he said according to the Moscow Times.

The opposition figures targeted in the video included Mikhail Kasyanov, a former prime minister and current leader of the Parnas political party.

It also showed Vladimir Kara-Murza, a Parnas deputy chief and project co-ordinator at the pro-democracy Open Russia initiative.

Russia's leading human rights advocate Lyudmila Alexeyeva, who heads the Moscow Helsinki Group, called the video a "direct threat", Govorit Moskva radio reported on its website.

The Kremlin has ignored the remarks by the Chechen leader, who proclaims unquestioning loyalty to Russian President Vladimir Putin and has publicly denounced opposition leaders in Russia as "traitors".

Last year he defended one of the Chechens charged with the murder of Boris Nemtsov, a former prime minister gunned down in Moscow in February 2015.

The head of the presidential human rights council, Mikhail Fedotov, said that Kadyrov's video was misinterpreted by those "who don't understand the language of metaphors", the Moscow Times reported.