Ukraine claims Russian chemical attack

(Kyiv, Ukraine) -- Fears are growing about a possible a chemical weapons attack in Ukraine.

Officials there claim Russian troops used a poisonous substance to target civilians and soldiers in Mariupol. The city has been under siege for weeks and is mostly destroyed.

Ukraine is still trying to confirm but warns if true, it crosses all boundaries. The Pentagon is monitoring the reports and deeply concerned.

Britain and Australia are also investigating.