White brightly burning munitions were shown cascading down on the Azovstal steel works in the Ukrainian port city of Mariupol in what a British military expert said looked like either an attack with phosphorus or incendiary weapons.
Reuters was not able to immediately identify the type of munitions being used or when the video was taken. It was posted on Sunday on the Telegram messaging application by Alexander Khodakovsky, a commander of the pro-Russian self-proclaimed republic of Donetsk.
“If you didn't know what it is and for what purpose - you could say that it's even beautiful,” Khodakovsky said in a message beside the video. Khodakovsky could not be immediately reached for comment.
It was not immediately clear which forces had fired the munitions, or from where.
Russian forces have pummeled Mariupol for nearly two months, but some Ukrainian fighters remain holed up in the vast Soviet-era plant founded under Josef Stalin and designed with a labyrinth of bunkers and tunnels to withstand attack.
Russia has not commented on what specific weapons it has used to attack the plant. The Russian defence ministry did not reply to a written request for comment about the video.
Ukraine's armed forces declined immediate comment.
White phosphorus munitions can be used on battlefields to make smoke screens, generate illumination, mark targets or burn bunkers and buildings. White phosphorus is not banned as a chemical weapon under international conventions.
Human rights groups have urged a ban on the use of phosphorus munitions because of the severe burns they cause. The United States used phosphorus munitions in the Vietnam war and the 2003-2011 Iraq war. Russia used them in the Chechen wars.
Petro Andryushchenko, an aide to Mariupol's mayor, said that Russia had used incendiary or phosphorous bombs on Azovstal. Andryushchenko was speaking from Ukrainian-controlled territory. Reuters was unable to immediately verify his comments.
Hamish Stephen de Bretton-Gordon, a former commanding officer of Britain's Joint Chemical, Biological, Radiological and Nuclear Regiment, said it looked very like phosphorus in the video, but only a sample could give absolute confirmation.
“It does look very much like white phosphorus rockets or artillery shells which are exploding just above the ground or upon the ground,” he told Reuters.
“It could possibly be Russian incendiary rockets as well but I have certainly seen a lot of white phosphorus in particularly Syria and it looks very much like that to me,” he said.
While some Ukrainian fighters are still in bunkers at the steel plant, civilians have been evacuated.