Ukraine has sharply denied Moscow allegations that it is preparing to use a so-called dirty, nuclear-tainted bomb.

The allegation raises suspicions that Moscow itself is up to something dirty, said Ukrainian President Volodymyr Zelenskyy on Sunday.

He called on the world community to resist an escalation of the eight-month-old war by Russia.

This was preceded by telephone calls between the Russian Defense Minister Sergei Shoigu and the ministers of the NATO countries Great Britain, France and Turkey.

In it he claimed on Sunday that Ukraine wanted to drop a nuclear-contaminated conventional bomb in order to blame it on Russia.

British Defense Secretary Ben Wallace and US Secretary of State Antony Blinken said it was not credible.

It was unusual that Shoigu and US Secretary of Defense Lloyd Austin spoke on the phone for the second time in three days on Sunday.

According to the Pentagon, Austin and Wallace also contacted each other after Schoigu's calls.

Experts did not rule out that because of military failures, Moscow itself could consider using such an explosive device.

On Monday, February 24th, it was exactly eight months ago that Russia invaded the neighboring country.

It is the 243rd day of defense for Ukraine.

A reconstruction conference for Ukraine with Chancellor Olaf Scholz (SPD) and Kiev Prime Minister Denys Schmyhal is to take place in Berlin on Monday.

Zelenskyj: Russia only leaves behind mass graves and destroyed country

"If anyone can use nuclear weapons in our part of Europe, there is only one - and this one ordered Comrade Shoigu to call there," said Zelenskyy, referring to Russian President Vladimir Putin.

The world must make it clear that it is not ready to swallow this "dirt".

"Wherever Russia goes, it leaves behind mass graves, torture camps, destroyed towns and villages, mined lands, destroyed infrastructure and natural disasters," the president said.

Ukraine, on the other hand, is trying to enable its people to lead normal lives again.

"Where Ukraine is, no life is destroyed."

"Russian lies about Ukraine's alleged plans to use a 'dirty bomb' are as absurd as they are dangerous," Foreign Minister Dmytro Kuleba wrote on Twitter.

Ukraine is loyal to the Nuclear Non-Proliferation Treaty.

"The Russians often blame others for what they are planning themselves."

Experts do not rule out escalation

Strategic stability requires a minimum of trust and reliable communication, disarmament expert Jean-Marie Guéhenno wrote on Twitter.

"When the Russian defense minister flatly lies to his colleagues, that's irresponsible and dangerous."