Russia-Ukraine crisis: Top developments you need to know

* Ukrainian President Volodymyr Zelenskiy vowed to stay in Kyiv as his troops battled Russian invaders who are advancing toward the capital in the biggest attack on a European state since World War Two. 

Read: Inflicted-800-casualties-among-Russian-forces-claims-.vpf

* A picture was emerging of fierce fighting across multiple fronts. Russian forces had captured the Chernobyl former nuclear power plant on the route between Belarus and Kyiv, a Ukrainian.

* Ukrainian forces downed an aircraft over Kyiv, which then crashed into a residential building, said Anton Herashchenko, an adviser to the interior minister. read more A missile hit a Ukrainian border post in the southeast, killing and wounding some guards, the border service said.

* Russian President Vladimir Putin said his aim was to demilitarize and "denazify" Ukraine. He said any hindrance would be met by "such consequences that you have never encountered in your history". read more 

* US President Joe Biden said Putin's action was about naked aggression. He unveiled new sanctions on its banks and wealthy elite and export restrictions. read more 

* French President Emmanuel Macron said he held a "frank, direct and quick" phone call with Putin on Thursday to ask him to stop military operations because Zelenskiy had asked him to.

* Britain, Canada, the EU, Australia, Japan, Taiwan and others unveiled sanctions against Russia, targeting banks, military exports and members of Putin's inner circle. 

* Thousands of Ukrainians sought to escape to neighbouring countries.

* Former heavyweight boxing champion Vitali Klitschko said he would take up arms alongside his brother and fellow Hall of Famer Wladimir Klitschko for Ukraine. 

* Stock markets tumbled and Russia's rouble hit an all-time low. US stocks turned positive as the West detailed its sanctions against Russia.

* The UN Security Council is expected to vote at 2000 GMT on a draft resolution condemning Russia and requiring it to unconditionally withdraw.

Read: Explosions heard in Kyiv as Russia presses Ukraine assault