Ukrainian officials warn Russian forces may have used chemical weapons in Mariupol

Ukrainian officials warned on Tuesday that Russian forces may have used chemical weapons while besieging the port city of city Mariupol – a charge that could potentially change the West’s strategy towards Russia as the war nears the end of the second month.

According to Ukraine’s Deputy Defense Minister Hanna Malyar, “There is a theory that these could be phosphorous munitions," adding that "official information will come later."

Pavlo Kyrylenko, the governor of Ukraine’s eastern Donetsk region, said he had seen incident reports from the attack, but noted that he could not yet confirm them.

"We know that last night around midnight a drone dropped some so-far unknown explosive device, and the people that were in and around the Mariupol metal plant, there were three people, they began to feel unwell," he told CNN.

Although Russia-backed separatists fighting in Mariupol have denied using chemical weapons, city officials have alleged that three soldiers from Ukraine’s Azov regiment were injured by "a poisonous substance" in an attack on Monday. 

Formal evidence to support the Ukrainian charges has yet to be presented, but Western leaders on Tuesday said they were aware of the reports and were working with Ukrainian officials on the ground to verify them, the Daily Mail reported.

On Tuesday, British Foreign Secretary Liz Truss said officials in London were working to “urgently” investigate the Kremlin’s “callous escalation.”

Similarly, Pentagon officials – who previously pledged that the use of chemical weapons by Russia could be met with firm retaliation -- called the Ukrainian accusations “deeply concerning.”

Although Russia announced that it would “drastically reduce” its military operations in Ukraine on Tuesday, Western officials have warned that the Kremlin will soon focus the entirety of its military force on Ukraine’s eastern regions.

Serhiy Gaidai , the governor of Luhansk region, urged residents to evacuate using agreed humanitarian corridors.

"It's far more scary to remain and burn in your sleep from a Russian shell," he wrote on social media. "Evacuate, with every day the situation is getting worse. Take your essential items and head to the pickup point."

Ukrainian President Volodymyr Zelensky pleaded for Western governments to send more strategic weapons to help end the siege of Mariupol and block Russia’s expected eastern offensive.

"Unfortunately we are not getting as much as we need to end this war faster...in particular, to lift the blockade of Mariupol," he said.

In an address to the Lithuanian parliament, Zelenskiy urged the European Union to impose sanctions on all Russian banks and Russian oil and to set a deadline for ending imports of Russian gas.

"We cannot wait," he said.