'Full-scale invasion': Ukraine vows to defend itself

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

Explosions could be heard before dawn in the Ukrainian capital Kyiv.

Ukraine's President Volodymur Zelenskiy said Kremlin leader Vladimir Putin's aim was to destroy his state.

At least eight people had been killed and nine were wounded by the Russian shelling, an advisor to the Ukrainian Minister of Internal Affairs said.

Putin declared in a televised address that he had ordered "a special military operation" to protect people, including Russian citizens who had been subjected to "genocide" in Ukraine , an accusation the West has long described as absurd propaganda.

"And for this we will strive for the demilitarisation and denazification of Ukraine," Putin said.

"Russia cannot feel safe, develop, and exist with a constant threat emanating from the territory of modern Ukraine ... All responsibility for bloodshed will be on the conscience of the ruling regime in Ukraine."

Ukraine, a democratic country of 44 million people, voted overwhelmingly for independence from Moscow after the fall of the Soviet Union and says it aims to join NATO and the European Union.

Putin, who denied for months that he was planning an invasion, has called Ukraine an artificial creation carved from Russia by enemies.

US President Joe Biden said his prayers were with the people of Ukraine "as they suffer an unprovoked and unjustified attack", while promising tough sanctions in response.

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EU foreign affairs chief Josep Borrell also promised the toughest financial sanctions the bloc had ever imposed.

"These are amon g the darkest hours of Europe since the Second World War," Borrell said.

The full scope of the Russian military operation was not immediately clear but Putin said: "Our plans do not include the occupation of Ukrainian territories. We are not going to impose anything by force."

Putin said he had ordered Russian forces to protect the people and appealed to the Ukrainian military to lay down their arms.

Zelenskiy appealed to world leaders to impose all possible sanctions on Russia, including on Putin.

Three hours after Putin gave his order, Russia's defence ministry said it had taken out military infrastructure at Ukrainian air bases and degraded its air defences, Russian media reported.

Earlier, Ukrainian media reported that military command centres in Kyiv and the city of Kharkiv in the northeast had been struck by missiles, while Russian troops had landed in the southern port cities of Odessa and Mariupol.

A Reuters witness later heard three loud b lasts in Mariupol. Russian-backed separatists in the east later said they had captured two towns, the RIA news agency reported.

Global stocks and US bond yields dived, while the US dollar and gold rocketed higher after Putin's address. Brent oil surged past $US100/barrel for the first time since 2014.

Queues of people waited to withdraw money and buy supplies of food and water in Kyiv. Traffic was jammed going west out of the city towards the Polish border.

Biden, who has ruled out putting US troops on the ground in Ukraine, said Putin had chosen a premeditated war that would bring a catastrophic loss of life and human suffering.

"Russia alone is responsible for the death and destruction this attack will bring, and the United States and its Allies and partners will respond in a united and decisive way," said Biden, who spoke to Zelenskiy by telephone.

French President Emmanuel Macron condemned Russia's action while NATO Secretary-General Jens Stoltenberg said NATO allies would meet to tackle th e consequences of Russia's "reckless and unprovoked attack".

UN Secretary-General Antonio Guterres made a last-minute plea to Putin to stop the war "in the name of humanity".

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Australian man Matt Williams, 25, is in Kharkviv and has been documenting the situation via his YouTube channel Willy Beating Cancer.

He vowed to stay despite being urged to flee when an invasion was imminent.

Mr Williams, who is from Kirkstall in south-west Victoria, said he was shocked.

"We've just woken up maybe half an hour ago via shelling," Mr Williams said on a video on his channel after news broke.

You can see his video below [language warning].

In Australia, Prime Minister Scott Morrison says sanctions placed on Russia will target individuals at the centre of "perpetrating" the Ukrainian invasion.

As of Friday, Australia will slap additional economic sanctions on Russia, targeting eight Russian security council members, banks, transport, energy and telecommunication companies.

Sanctions imposed by Australia follow similar moves by the United States and the United Kingdom and come after Russia's decision to move troops into the eastern Ukrainian region of Luhansk and Donetsk.

Mr Morrison said there has to be a price for "unprovoked, unlawful, unwarranted, unjustified attacks" on another nation's sovereignty.

Ukrainian Australians have condemned Russia after President Vladimir Putin announced a military operation in separatist-held regions in the country's southeast.

The Australian Federation of Ukrainian Organisations says Russia's decision to recognise the control of "terrorist organisations" in Luhansk and Donetsk is provocative and dangerous.

"Such a step is another act of aggression against Ukraine, its independence, sovereignty and territorial integrity," AFUO co-chair Stefan Romaniw said.

"It demonstrates Russia's decision to choose a path of global isolation and aggression against the international rules-based order."

Mr Romaniw said resistance in Ukraine has grown since the 2014 annexation of Crimea and civil society remained strong.

"I have spoken today to Ukrainians in Odessa, and they have told me that on the street, at every intersection, in every building and every house, Putin will find resistance," he said.

"We are ready to fight."

- Reuters/AAP/PA