The Ukrainian authorities are declaring martial law across the country, President Vladimir Zelensky announced in a video posted on his Telegram channel on Thursday.

"We are declaring martial law across the country," he said.

The Russian troops delivered strikes against Ukrainian military infrastructure facilities, Zelensky said.

"Russia delivered strikes against our military infrastructure and our border guards, border guard units. Explosions were heard in many cities of Ukraine," Zelensky said in a video posted on his Telegram channel.