President Vladimir Putin told Western countries on Thursday they risked provoking a nuclear war if they sent troops to fight in Ukraine, warning that Moscow had the weapons to strike targets in the West.

The war in Ukraine has triggered the worst crisis in Moscow's relations with the West since the 1962 Cuban Missile Crisis. Putin has previously spoken of the dangers of a direct confrontation between NATO and Russia, but his nuclear warning on Thursday was one of his most explicit.

Addressing lawmakers and other members of the country's elite, Putin, 71, repeated his accusation that the West was bent on weakening Russia, and he suggested Western leaders did not understand how dangerous their meddling could be in what he cast as Russia's own internal affairs.

He prefaced his nuclear warning with a specific reference to an idea, floated by French President Emmanuel Macron on Monday, of European NATO members sending ground troops to Ukraine - a suggestion that was quickly rejected by the United States, Germany, Britain and others.

"(Western nations) must realise that we also have weapons that can hit targets on their territory. All this really threatens a conflict with the use of nuclear weapons and the destruction of civilisation. Don't they get that?!" said Putin.

Speaking ahead of a March 15-17 presidential election when he is certain to be re-elected for another six-year term, he lauded what he said was Russia's vastly modernised nuclear arsenal, the largest in the world.

"Strategic nuclear forces are in a state of full readiness," he said, noting that new-generation hypersonic nuclear weapons he first spoke about in 2018 had either been deployed or were at a stage where development and testing were being completed.

Visibly angry, Putin suggested Western politicians recall the fate of those like Nazi Germany's Adolf Hitler and France's Napoleon Bonaparte who had unsuccessfully invaded Russia in the past.

"But now the consequences will be far more tragic," said Putin. "They think it (war) is a cartoon," he said, accusing Western politicians of forgetting what real war meant because they had not faced the same security challenges as Russians had in the last three decades.

MORE TROOPS FOR WESTERN BORDER

Russian forces now had the initiative on the battlefield in Ukraine and were advancing in several places, Putin said. Russia must also boost the troops it has deployed along its western borders with the European Union after Finland and Sweden decided to join the NATO military alliance, he added.

The veteran Kremlin leader dismissed Western suggestions that Russian forces might go beyond Ukraine and attack European countries as "nonsense". He also said Moscow would not repeat the mistake of the Soviet Union and allow the West to "drag" it into an arms race that would eat up too much of its budget.

"Therefore, our task is to develop the defence-industrial complex in such a way as to increase the scientific, technological and industrial potential of the country," he said.

Putin said Moscow was open to discussions on nuclear strategic stability with the United States but suggested that Washington had no genuine interest in such talks and was more focused on making false claims about Moscow's alleged aims.

"Recently there have been more and more unsubstantiated accusations against Russia, for example that we are allegedly going to deploy nuclear weapons in space. Such innuendo... is a ploy to draw us into negotiations on their terms, which are favourable only to the United States," he said.

"...On the eve of the US presidential election, they simply want to show their citizens and everyone else that they still rule the world."