The commander of a Ukrainian unit defending the port city of Mariupol posted a video statement Tuesday, saying a handful of people had been affected by a "poisonous substance of unknown origin" amid reports of an alleged Russian chemical attack.
Denys Prokopenko, commander of the Azov battalion, said in the statement that it was not possible to investigate the scene fully due to Russian shelling.
"The victims of the spread of a poisonous substance of unknown origin in the city of Mariupol are in a relatively satisfactory condition," Prokopenko said.
"Contact of the civilians with the substance was minimal, for the [incident] epicenter was at a certain distance from the location of the civilians. The military were a little bit closer.
However, it is currently impossible to fully investigate the scene due to the enemy fire, because the Russians continue using the tactics of concealing their own crimes."
CNN cannot independently verify that there was any kind of chemical strike, or how many casualties were caused by any such incident.
Prokopenko's post on Telegram shows brief interviews with a soldier and two civilians, including an elderly woman, who were purportedly affected by the substance, and interviews with two medical personnel.
An unnamed military anesthesiologist said main symptoms of the victims are the following: facial hyperemia, high blood pressure, dryness and inflammation in the oropharynx and mucous membranes of the eyes.
Maksym Zhorin, a co-commander of Azov, called the incident a "brazen crime," adding, "Many of us did not believe that they would do it. But, probably out of desperation that they could not seize Mariupol for more than a month, they resorted to such cynical crimes and began to use chemical weapons."
Zhorin said three people had experienced serious symptoms. "All the others were in a shelter at the time and were not affected that much," he said.
In remarks on national television, Ukrainian Deputy Minister of Defense Hanna Maliar said authorities were still investigating the incident.
"As of now we are checking this information," she said. "We are trying to understand what was used. Based on preliminary data, there's an assumption that these could have been phosphorus munition. But the official information will follow later."
We have to understand there's a very real threat of chemical weapons use."
The Azov battalion, which had its origins as a far-right militia and was folded into Ukraine's armed forces, is one of the units holding out in the besieged port city.
Some background: In response to the reports, Britain’s junior Armed Forces minister said "all options are on the table" for how the West will respond if Russia uses chemical weapons in Ukraine.
"I think it’s useful to maintain some ambiguity [...] over exactly what the response would be, but let’s be clear, if they are used at all, then [Russian] President [Vladimir] Putin should know that all possible options are on the table in terms of how the West might respond," James Heappey told Sky News.
According to Human Rights Watch, "white phosphorus can burn people to the bone, smolder inside the body, and reignite when bandages are removed."
The munitions are either banned or circumscribed under international law in populated areas.