KYIV — Ukraine slammed Russia on Sunday for alleging Kyiv was planning to use a radioactive bomb in its own territory, calling the claims "dangerous" lies and prompting Western allies to warn Moscow against using any pretext for escalating the conflict.

Russia's Defense Minister Sergei Shoigu spoke with his British, French and Turkish counterparts to convey "concerns about possible provocations by Ukraine with the use of a 'dirty bomb'," Moscow said, referring to a weapon that uses traditional explosives to scatter radioactive material.

But Ukraine and its Western allies swiftly dismissed Moscow's allegations, with the United States, Britain and France issuing a joint statement on Sunday rejecting Russia's "transparently false" claims.

Moscow said Shoigu had also spoken to US Defense Secretary Lloyd Austin, but the Pentagon said Austin had "rejected any pretext for Russian escalation" in the phone call.

US Secretary of State Antony Blinken tweeted on Sunday that he spoke to Ukraine's Foreign Minister Dmytro Kuleba to "reject Russia's false allegations that Ukraine is preparing to use a dirty bomb on its own territory".

Ukrainian President Volodymyr Zelensky called for a united international response.

"If Russia calls and says that Ukraine is allegedly preparing something, it means one thing: Russia has already prepared all this," Zelensky said in a video address on social media.

"I believe that now the world should react as harshly as possible."

Earlier on Sunday, Kuleba had denounced Moscow's claims as "absurd" and "dangerous".

"Russians often accuse others of what they plan themselves," he added.

A British defence ministry statement said Defence Secretary Ben Wallace had "refuted these claims and cautioned that such allegations should not be used as a pretext for greater escalation".

And in Washington, National Security Council spokeswoman Adrienne Watson said President Joe Biden's administration dismissed Moscow's "transparently false allegations".

'VILE STRIKES'

Russia announced Sunday it had destroyed a depot in central Ukraine that was storing over 100,000 tonnes of aviation fuel.

Kyiv's energy operator said scheduled power cuts had been introduced in the capital due to Russia's repeated strikes on Ukraine's power network, and urged residents to use electricity sparingly.

More than 1 million Ukrainian households have lost electricity following recent Russian strikes and at least a third of the country's power stations have been destroyed ahead of winter, according to officials in Kyiv.

Zelensky condemned the strikes as "vile".

'SAVE YOUR STRENGTH'

In the southern Ukrainian city of Kryvyi Rig, deputy mayor Sergiy Miliutin has been dealing with emergencies and outages from his underground bunker, used as a venue for a children's martial arts competition.

"I've reached a point where I just survive on my drive. You have to stay level-headed and save your strength. No one knows how long this will all last," he told AFP.

The intensification of Russian strikes on Ukraine, particularly on energy facilities, came after the bridge linking the annexed Crimea peninsula to mainland Russia was partially destroyed by an explosion this month.

It was another major setback for Moscow's forces, battling to contain a Ukrainian counteroffensive in the south and east of the country.

Speaking in Rome on Sunday at the start of a peace conference, French President Emmanuel Macron said that it was for Ukrainians to decide when "peace is possible".

Ukraine reported 3 deaths in an overnight Russian artillery strike in the Toretsk area, a governor of the eastern Donetsk region said.

Inside Russia, 2 lines of defense have been built in the border region of Kursk to deal with any possible attack, a local governor said Sunday.

And defense structures are also being built in the neighboring Russian border region of Belgorod after two civilians were killed there in strikes Saturday and thousands were left without electricity, according to governor Vyacheslav Gladkov.

KHERSON EVACUATIONS

Ukraine's SBU intelligence service said it had detained 2 officials of Ukrainian aircraft engine maker Motor Sich on suspicion of working with Russia.

The SBU said management at the company's plant in Ukraine's southern Zaporizhzhia region -- partly controlled by Russian forces -- had colluded with Russian state-owned defense conglomerate Rostec.

The suspects had supplied Russia with Ukrainian aircraft engines that were used to make and repair attack helicopters, the SBU said.

In the southern Ukrainian region of Kherson, which Russia claims to have annexed, pro-Moscow officials have urged residents to leave amid Ukraine's counteroffensive.

Kherson, the region's main city, was the first to fall to Moscow's troops in the invasion's early days and retaking it would be a major prize for Kyiv.

Around 25,000 people have already left Kherson city to the left bank of the Dnipro River, according to Kremlin-installed officials.

Ukraine has denounced the removal of residents from Kherson, describing them as "deportations".

© Agence France-Presse