Mariupol has almost disappeared from weeks of heavy Russian bombing. Caption image: Mariupol has almost disappeared from weeks of heavy Russian bombing. “There have been” reports that Russian forces may have used chemical agents in an attack on the people of Mariupol, “UK Foreign Secretary Liz Tras wrote on Twitter. “We are working urgently with partners to verify details. Any use of such weapons would be a harsh escalation in this conflict and we will keep [Russian President Vladimir] “Putin and his regime must be held accountable.” This comes shortly after fighters of Ukraine’s Azov regiment defending Mariupol said Monday that Russian troops had “used a poisonous substance of unknown origin against Ukrainian forces and civilians” in the besieged southern port city. She did not provide any evidence to support her claim. Petro Andriusenko, assistant mayor of Mariupol, wrote in his Telegram channel that reports of a chemical attack have not been confirmed and that he is expected to provide clarifications later. The Pentagon said the United States was aware of “reports on social media” about allegations that Russian forces had used possible chemical munitions in Mariupol, but also made it clear that this had not been confirmed. “We can not confirm at this time and we will continue to monitor the situation closely,” said John Kirby, a Pentagon spokesman. Ukrainian President Volodymyr Zelensky raised the issue in a video conference late Monday. “One of his mouthpieces [Russian] the occupiers stated that they could use chemical weapons against the defenders of Mariupol. “We are taking it as seriously as possible.” Zelensky did not elaborate. Russia has not commented publicly on the matter. Western and Ukrainian officials have accused Moscow of plotting to use chemical weapons in Ukraine since the beginning of the conflict, but no such attack has been documented. See more on twitterSee more on twitter