'Darkest hours of Europe' as Russia invades Ukraine

Putin authorises military operation in east; explosions heard in Kyiv and across Ukraine, Kyiv declares martial law, urges 'all possible' sanctions

Russian forces invaded Ukraine by land, air and sea on Thursday, confirming the worst fears of the West with the biggest attack by one state against another in Europe since World War Two.

Russian missiles rained down on Ukrainian cities. Ukraine reported columns of troops pouring across its borders into the eastern Chernihiv, Kharkiv and Luhansk regions, and landing by sea at the port cities of Odessa and Mariupol in the south.

Explosions could be heard before dawn in the capital Kyiv.

Gunfire rattled out near the main airport and sirens blared across the city.

Ukraine's President Volodymur Zelenskiy said Kremlin leader Vladimir Putin's