According to Ukraine's state service of special communications, "A rocket hit a residential building in the centre of Chernihiv.

A fire broke out, two lower floors are on fire. The number of injured is currently unknown.

"Earlier, the agency had said blasts were heard in Kyiv and Kharkiv in the morning.

"Explosions are heard again in Kyiv and Kharkiv. Before that, it was calm in the Ukrainian capital for several hours," it added.

The Kyiv Independent had also reported an air raid alert that sounded in the city in the early morning.

Earlier, Ukrainian president Volodymyr Zelenskiy in a telephonic conversation with British Prime Minister Boris Johnson said "the next 24 hours was a crucial period for Ukraine"..

The UK has said that additional 40 million pound will be sent to provide vital medical supplies and assistance to Ukraine.

Amid the Ukraine-Russia situation, the UNSC has for the first time since 1982 called for a UNGA emergency special session.

It will be held on Monday. Abdulla Shahid, President of the 76th session of the United Nations General Assembly will preside over the Session.

(With UNI inputs)