According to diplomats, the UN Security Council will have a closed-door meeting on Tuesday to address Russia's allegations that Ukraine intends to explode a "dirty bomb" and blame it on Moscow.
In a letter to the council and UN Secretary-General Antonio Guterres that AFP obtained, Russia's UN envoy, Vasily Nebenzya, reiterated the charge that Kiev was preparing such a provocation.
Kiev and its Western allies denied the claim as Russia suffered serious defeats eight months into its invasion of Ukraine.
In telephone conversations with NATO allies on Sunday, Sergei Shoigu, the Russian defense minister, alleged that Ukraine intended to explode a crude bomb that might spew dangerous nuclear, chemical, or biological weapons.
In a joint statement released on Sunday, the United States, France, and Britain disputed that, alleging it was a plot by Moscow to escalate the conflict.
They added that "the world will see through any attempt to exploit this claim as a pretext for escalation."
The British UN mission restated its position in a tweet sent before the Security Council meeting.
It stated, "Reminder: Ukraine has no nuclear weapons."