Volodymyr Zelenskyy said that weapons would be issued to any Ukrainian who wants one and appealed for blood donations for wounded soldiers.

He added that the enemy had suffered "serious losses".

Ukraine 'attacked from Russia, Belarus and Crimea' - latest live updates

It comes after Russian President Vladimir Putin ordered a "specialised military operation", heralding the start of an invasion of Ukraine.

Sky News heard explosions in Kyiv and Kharkiv and understands that borders have been breached in at least four areas of Ukraine.

Ukraine's foreign minister Dmytro Kuleba said: "Putin has just launched a full-scale invasion of Ukraine."