Il Nuovo Postiglione - Ukrainian and Russian fight on streets of capital Kyiv

Russian leader Vladimir Putin unleashed a full-scale invasion on Thursday that has killed dozens of people, forced more than 50,000 to flee Ukraine in just 48 hours and sparked fears of a new Cold War in Europe.

Western nations announced personal sanctions targeting Putin as his soldiers advanced into Ukraine, while Zelensky urged the nation to defend itself.

"Special attention on Kyiv –- we cannot lose the capital," he said.

"I am turning to our defenders, male and female, on all fronts: this night the enemy will use all the forces it has to crush our defence in a treacherous, harsh and inhumane way," he said.

"Tonight they will attempt a storming" of the capital, he added.

Zelensky, who earlier called for a stronger response from the West, said he spoke to leaders including French President Emmanuel Macron, German Chancellor Olaf Scholz and US President Joe Biden.

"We have agreed on more aid, more support, significant support for our state," he said.

- Body on the pavement -

Civilians prepared to face off with the heavily armed Russian forces have collected assault riffles and were urged by the Ukrainian defence ministry "to make Molotov cocktails and neutralise the enemy".

"I only took a weapon in my hands for the first time yesterday," paragliding instructor turned volunteer fighter Roman Bondertsev said. "We will try our best."

In Kyiv's city centre, AFP journalists heard loud explosions early Saturday.

"Heavy fighting continues," the State Special Communications Service of Ukraine posted on its telegram account around 0330 GMT.

Earlier Saturday, Ukraine's military said Russia had "attacked one of the military units on Victory Avenue in Kyiv" but that the assault was "repulsed".

It also reported another incident northwest of the capital.

AFP saw a dead man in civilian clothes lying sprawled on the pavement as nearby medics rushed to help another man whose car was crushed by an armoured vehicle.

Kyiv said that 137 people, including soldiers and civilians, have been killed.

Meanwhile, the country's Defence Ministry said "two enemy targets were shot down" -- identifying them as a Russian SU-25 helicopter and a military bomber -- near the separatist zone in the east.

A Russian transport plane had also been "knocked down" near Vasylkiv, a town roughly 30 kilometres (19 miles) southwest of Kyiv, the ministry added on its official Facebook page.

Earlier, small arms fire and explosions were heard in the capital's northern district Obolonsky as what appeared to be an advance party of Russia's invasion force left a trail of destruction.

Ukrainian forces reported fighting with Russian armoured units in two locations between 40-80 kilometres north of Kyiv.

The Ukrainian defence ministry said that 2,800 Russian soldiers had been killed, without providing evidence.

Moscow has yet to report on casualties.

- 'Point of no return' -

The United States, Canada, Britain and the European Union doled out further sanctions on Russia on Friday, including against Putin and Foreign Minister Sergei Lavrov.

The EU foreign policy chief Josep Borrell called it the "harshest" package ever drawn up by the bloc.

The UK government ordered all assets of both men frozen while the United States and Canada will also impose sanctions on the pair, with Washington including a travel ban.

Russia said the sanctions against the pair were "a demonstration of the complete impotence of the foreign policy" of the West.

"We have reached the line after which the point of no return begins," Russian foreign ministry spokeswoman Maria Zakharova said.

Moscow also vetoed a UN Security Council resolution that deplored "in the strongest terms" Russia's invasion, while China, India and the United Arab Emirates abstained.

Putin had earlier described the Ukrainian government as "terrorists" and "a gang of drug addicts and neo-Nazis", urging the country's military to topple Zelensky.

The Ukrainian leader responded by vowing to stay and defend the capital.

"We're all here. Our military is here. Citizens in society are here. We're all here defending our independence, our country, and it will stay this way," he said in the self-shot video from Kyiv.

- 'Not real diplomacy' -

A Kremlin spokesman said Putin was ready to send a delegation to Belarusian capital Minsk "for talks with a Ukrainian delegation".

But the US swiftly dismissed the offer.

After invading Ukraine, "now we see Moscow suggesting diplomacy take place at the barrel of a gun. This is not real diplomacy," State Department spokesman Ned Price said.

The UN said that more than 50,000 Ukrainians had fled the country in the past two days, calling for "safe unimpeded access" for aid operations.

Streams of people in cars and on foot were seen crossing into Hungary, Poland and Romania while hundreds camped out in a train station in the Polish border city of Przemysl.

About 100,000 people are believed to be internally displaced.

The US-led military alliance NATO said it was deploying its rapid response forces for the first time to bolster defences on the alliance's eastern flank.

Facebook also unveiled new restrictions, demonetising Russian state media across its platform.

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F.Criscuolo--INP