Great Britain is verifying Russia's claim to use chemical weapons

United Kingdom Foreign Secretary Liz Trus has indicated there have been reports that Russian forces may have used chemical agents in an attack on the people of Marioupolis.

“We are working urgently with partners to verify details. Any use of such weapons would be a heartless escalation in this fight”, it wrote on Twitter.

This comes shortly after fighters from Ukraine's Azov regiment protecting Marioupoli said Russian troops used a toxic substance of unknown origin against Ukrainian forces and civilians in the besieged southern port city.

Petro Andryuschenko, an assistant to Marioupolis Mayor, said reports of a chemical attack had not been confirmed and that he expected to provide clarification later.

US Defence Department spokesman John Kirby said such a thing cannot be confirmed immediately, reports the BBC.

“We can't confirm it at this moment, we will continue to monitor the situation closer to”, he said.

Ukrainian President Volodymyr Zelensky touched the issue in his final speech.

“One of the spokespersons of the Russian invaders said they could use chemical weapons against Marioupolis people. We treat this with the greatest seriousness”, Zelensk has indicated.

Russia has not commented publicly on the issue.

Western and Ukrainian officials have accused Moscow of planning the use of chemical weapons in Ukraine since the beginning of the conflict, but no such attack has yet been confirmed.