Russian journalist and Nobel Peace Prize laureate Dmitry Muratov decried Tuesday Russian propaganda arguing for using nuclear weapons in the Ukraine conflict, warning that would signal "the end of humanity".

"I would not rule out the possibility that nuclear weapons might be used," Muratov told journalists in Geneva, speaking through a translator.

The Kremlin said it had placed Russian nuclear forces on high alert shortly after its invasion of Ukraine began February 24.

And amid increasing Western support to Ukraine, Russian President Vladimir Putin has made thinly veiled threats hinting at a willingness to deploy Russia's tactical nuclear weapons, which Russian military doctrine holds can be used to force an adversary to retreat.

Speaking at an event marking the World Press Freedom Day, Muratov, whose own Novaya Gazata newspaper has been forced to suspend publication amid Moscow's military intervention, warned that the Kremlin's "propaganda warriors" were striving to make nuclear weapons use more palatable to the Russian public.

"For two weeks now, we have been hearing from our television screens that nuclear silos should be opened," he said.

"And we also hear that these horrible weapons should be used should the supplies of weapons to Ukraine continue," he said, referring to the push by the United States, the European Union and others to arm the war-torn country.

Contrary to the propaganda narrative, deploying such weapons would "not be the end of the war," he warned.

"This will be the end of humanity."

Nobel Peace Prize laureate Dmitry Muratov
Nobel Peace Prize laureate Dmitry Muratov warned no one can stop President Putin if he decides to use nuclear weapons Photo: AFP / Fabrice COFFRINI