NATO has condemned Vladimir Putin for "dangerous" nuclear rhetoric after the Russian president announced plans to station tactical nuclear weapons in Belarus, while Russian forces intensified shelling of the frontline Ukrainian city of Avdiivka.

The move, while not unexpected, is one of Russia's most pronounced nuclear signals yet and a warning to NATO over its military support for Ukraine, which has called for a meeting of the UN Security Council in response.

"Russia's nuclear rhetoric is dangerous and irresponsible," NATO spokeswoman Oana Lungescu said yesterday.

"NATO is vigilant and we are closely monitoring the situation. We have not seen any changes in Russia's nuclear posture that would lead us to adjust our own."

Mr Putin's non-proliferation pledge and his description of US weapons deployment overseas were way off the mark, she added.

"Russia's reference to NATO's nuclear sharing is totally misleading. NATO allies act with full respect of their international commitments," she said in a statement.

"Russia has consistently broken its arms control commitments."

The Kremlin on Monday said Western criticism would not change its plans.

"Such a reaction of course cannot influence Russian plans," Kremlin spokesman Dmitry Peskov said.

Speaking during a televised interview on Saturday, Putin said Moscow would station the tactical nuclear weapons "without violating our international agreements on nuclear non-proliferation".

He said this was "nothing unusual".

"The United States has been doing this for decades. They have long placed their tactical nuclear weapons on the territory of their allies," Putin said.

The Russian leader said he spoke to his Belarusian ally Alexander Lukashenko and that they had "agreed to do the same".

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Ukraine's security chief, Oleksiy Danilov, said Russia's plan would destabilise Belarus, which he said had been taken "hostage" by Moscow.

Others too joined the chorus of condemnation yesterday, with Lithuania saying it would call for new sanctions against Moscow and Minsk, while EU policy chief Josep Borrell urged Belarus not to host the weapons and threatened further sanctions.

Belarus and Russia have close military ties, and Minsk allowed Moscow to use Belarusian territory as a staging point for its full-scale invasion of Ukraine last year.

Experts said Russia's move was significant since it had until now been proud that unlike the United States, it did not deploy nuclear weapons outside its borders.

It may be the first time since the mid-1990s that it has done so.

Russian President Vladimir Putin in the Kremlin on Saturday

The US played down concerns about Russia's planned nuclear deployment.

Representative Michael McCaul, the Republican chairman of the US House of Representatives foreign affairs committee, said he regarded Russia's plan as designed to intimidate the West.

"I think this is sabre-rattling on the part of Putin basically to try to frighten," Mr McCaul told Fox News.

"These tactical nukes are disturbing."

Tactical nuclear weapons refer to those used for specific gains on a battlefield rather than those with the capacity to wipe out cities.

It is unclear how many such weapons Russia has, given it is an area still shrouded in Cold War secrecy.

A Ukrainian T-72 tank fires at Russian positions on the front line near Bakhmut

'Post-Apocalyptic' Avdiivka

On the battlefield, Russian shelling forced a nearly full shutdown of the eastern Ukrainian city of Avdiivka, which lies some 90km southwest of the besieged Bakhmut, the top local official said yesterday.

"I am sad to say this, but Avdiivka is becoming more and more like a place from post-apocalyptic movies," the city's military administration head Vitaliy Barabash said.

Yesterday, Russian shelling targeted two high-rise buildings in Avdiivka, which is just 10 km from the northern outskirts of Donetsk city, which has been under Moscow's control since 2014.

The Ukrainian military warned last week that Avdiivka could become a "second Bakhmut" - where fierce fighting described by both sides as a "meat grinder" has turned the town into rubble.

Ukraine's General Staff said yesterday its forces had repelled 85 Russian attacks during the past 24 hours across the eastern front, including the Bakhmut area.

Russia's defence ministry said yesterday that its forces had struck military targets in Kharkiv, Donetsk, Zaporizhzhia and Kherson regions, causing significant Ukrainian casualties.

The ministry also said it had downed a Ukrainian drone south of Moscow yesterday, adding three people were injured and apartment blocks were damaged in the drone attack.

Russia has said in the past that Ukrainian drones have flown into its territory and caused damage to civilian infrastructure, an assertion Kyiv denies.

Reuters could not verify the battlefield reports.

UN nuclear watchdog chief in Zaporizhzhia

Ukrainian President Volodymyr Zelensky and UN nuclear watchdog chief Rafael Grossi on Monday said they were visiting the southern frontline region of Zaporizhzhia, partly controlled by Russian forces.

"I met Zelensky today in Zaporizhzhia City and had a rich exchange on the protection of the Zaporizhzhia NPP (nuclear power plant) and its staff," Grossi wrote on Twitter.

"I reiterated the full support of the IAEA to Ukraine's nuclear facilities," he said, referring to the International Atomic Energy Agency which he heads.

Zaporizhzhia is home to Europe's largest nuclear power plant, which Russia captured a year ago.

Earlier on Monday Zelensky said he visited Ukrainian military positions in the Zaporizhzhia region.

It came after he visited the southern region of Kherson last week as well as military positions in the eastern Donetsk region.

German Leopard tanks delivered to Ukraine

Germany has delivered promised Leopard battle tanks to Ukraine, Chancellor Olaf Scholz said, providing Kyiv with much-needed heavy weaponry against Russia.

"Yes, we delivered Leopard tanks as we announced," Mr Scholz told a press conference with Dutch Prime Minister Mark Rutte in Rotterdam when asked to confirm a report in news outlet Spiegel.

The report said Berlin had delivered 18 of the advanced Leopards, with the last of the tanks having left Germany at the end of last week, before being handed over to Ukraine at the border.

Under German law, any country wanting to send Leopard tanks to another country must first get approval from Berlin (file image)

About 40 Marder infantry fighting vehicles had also arrived in Ukraine, Spiegel said, adding Berlin was keeping the route of the deliveries secret for security reasons.

The German defence ministry declined to comment when contacted by AFP.

Ukrainian soldiers were trained on the 2A6s, the most advanced of the Leopard models, on German military bases.

At the end of January, Berlin finally gave the green light for German-made Leopards -- among the world's most advanced tanks and used by militaries across Europe -- to be sent to Ukraine.

Under German law, any country wanting to send the tanks to another country must first get approval from Berlin.

Mr Scholz's government initially said it was aiming to assemble, along with allies, two battalions of tanks for Kyiv -- about 60 tanks in total.

But they have since struggled to get the numbers together.

The German and Dutch cabinets held a special joint session in the port city of Rotterdam at the huge, mirrored depot of the Boijmans Van Beuningen art museum.

Mr Scholz and Mr Rutte said they had discussed military support for Ukraine and their "unique" military cooperation, which involved Germany and the Netherlands merging some of their armed units.