Blasts could be heard in Kyiv after an air raid alert on Thursday morning, Reuters witnesses said, as authorities sent rescue teams to at least two locations in the Ukrainian capital.

Air defences are at work and rescuers are on their way to possible blast sites in the city's eastern and southern districts, city Mayor Vitali Klitschko wrote on the Telegram messaging app.

Missile debris fell in central Kyiv and non-residential buildings were damaged in the east, causing a fire, he said, with some people seeking medical help.

Officials and local media also reported blasts in Ukraine's Kharkiv, Khmelnytskiy, Rivne, Lviv and Ivano-Frankivsk regions. (Reporting by Reuters; Editing by Himani Sarkar and Gerry Doyle)