Poland, a NATO member, and a staunch supporter of Ukraine, shares a border with both Russia's Kaliningrad exclave and with Belarus, Moscow's ally.

"If our allies decide to deploy nuclear arms on our territory as part of nuclear sharing, to reinforce NATO's eastern flank, we are ready to do so," Duda said in an interview published by the Fakt daily.

Moscow in response warned it would take steps to "ensure its security" if Warsaw had the weapons.

Duda spoke to the Polish media after a visit to New York, where he held meetings at the UN and discussed the war in Ukraine with former US president Donald Trump.

In March, he visited Washington DC, where he met with US President Joe Biden.

Discussions about nuclear cooperation between Poland and the United States have been ongoing "for some time", he said.

"I have already talked about this several times. I must admit that when asked about it, I declared our readiness," Duda said.

"Russia is increasingly militarising Kaliningrad. Recently it has been relocating its nuclear weapons to Belarus," he added.

The Kremlin said it would respond if Poland hosted nuclear weapons.

"The military will of course analyse the situation and in any case will take all necessary response steps in order to ensure our security," Kremlin spokesman Dmitry Peskov told reporters.

In June 2023, Russian President Vladimir Putin confirmed that Russia had sent tactical nuclear arms to Belarus, which borders Ukraine and Poland.

During the last NATO summit in Vilnius, the allies pledged to "take all necessary steps to ensure the credibility, effectiveness, safety and security of the nuclear deterrent mission."