NICOLA Sturgeon has called for Russia to face the "severest consequences" after it launched an invasion of Ukraine.

Scotland's First Minister said the military action is "appalling and horrific" as missile strikes and explosions are reported in major cities.

Sturgeon called Vladimir Putin's decision to invade "unprovoked" as she stepped up calls for the UK to dramatically increase sanctions on Russia.

The First Minister said: "Overnight developments in Ukraine - however anticipated - are appalling and horrific.

"The Kremlin must face the severest consequences for this unprovoked aggression.

READ MORE: Russia launches 'full-scale' invasion on Ukraine

"And the world must stand in solidarity with the people of Ukraine."

Boris Johnson led a crisis meeting on Thursday of senior ministers and officials to consider how to respond to Putin’s military action against Ukraine.

The Prime Minister said the Russian president has “chosen a path of bloodshed and destruction”, and is expected to announce further sanctions.

The Prime Minister – whose initial package of sanctions was criticised by senior Tories and opposition figures – has promised to respond “decisively” to the Russian onslaught.

Putin announced the action during a televised address early on Thursday morning, saying the move was a response to threats from Ukraine.

He said Russia does not have a goal to occupy Ukraine, but the responsibility for bloodshed lies with the Ukrainian “regime”.

READ MORE: UK flights ordered to avoid Ukraine airspace after Russia launches invasion

Meanwhile, aircraft flying to or from UK airports are being ordered to avoid Ukraine airspace.

Transport Secretary Grant Shapps said he made the decision “following the horrific events overnight” as Russia launched a major military assault.

On Wednesday Sturgeon met the acting consul general of Ukraine, Yevhen Mankovskyi, and Linda Allison, the chairwoman of the Scottish branch of the Association of Ukrainians in Great Britain.

In the wake of those talks she urged the UK to impose tougher sanctions against Russia, saying while there had been “some very tough rhetoric from Boris Johnson” this now needed to be “matched by action”.