A spokesman for Moscow-backed separatists in eastern Ukraine has denied using chemical weapons to uproot Ukrainian troops in the port city of Mariupol. Eduard Basurin was quoted by the Interfax news agency as saying Tuesday that the separatist forces “haven’t used any chemical weapons in Mariupol.” Basurin’s assertion followed his statement Monday on Russian state TV that the separatists will use “chemical troops” against Ukrainian soldiers holed up at reinforced positions at a giant steel factory in Mariupol “to smoke them out of there.” A Ukrainian unit defending Mariupol claimed without providing evidence that a drone had dropped a poisonous substance on its positions. It indicated there were no serious injuries.