Ukraine

Russian forces have continued to pound Kyiv and other cities with artillery and cruise missiles in a campaign that has sent hundreds of thousands of Ukrainians fleeing westwards towards the European Union, clogging major highways and railway lines.

Top Russian security official and ex-president Dmitry Medvedev said military operations would be waged relentlessly until President Vladimir Putin's goals were achieved, ratcheting up Moscow's rhetoric.

Tens of thousands of people have already crossed into five countries bordering western Ukraine.

Poland alone has reported more than 50,000 arrivals in two days, while thousands more have streamed further south into Moldova, Romania, Hungary and Slovakia.

Most of those fleeing the invasion are women and children, as all men aged 18 to 60 are being told to stay and fight. BBC correspondents met them at the borders.

Almost exactly 30 years after the devastating siege of Sarajevo, another major European capital came under heavy bombardment with shells hitting apartment blocks, driving up the civilian death toll.

After the second day of the invasion, it was clear that it was being fiercely resisted, but also that Russia had much more military might yet to be unleashed on its neighbour.

Wearing a military uniform, Volodymyr Zelensky addressed the nation as Russia continued its attack on several fronts, moving closer to the capital.

Exact casualty numbers are unclear, but include Ukrainian civilians.

UN estimates suggest that more than 100,000 people have already fled from their homes.

Thousands have crossed into Moldova and Romania.

Russian President Vladimir Putin says his aim is to demilitarise and 'denazify' Ukraine.

Missiles rained down on Ukrainian cities and explosions were heard near the capital Kyiv. Ukraine's military said it destroyed four Russian tanks near the eastern city of Kharkiv, killed 50 troops in the Luhansk region and downed a sixth Russian aircraft.

Ukrainian President Volodymyr Zelensky urged all citizens prepared to defend the country to come forward, saying Kyiv would issue weapons to everyone who wants them.

As Russian air strikes hit overnight, many packed up and left Kyiv for the countryside or the border with the European Union.

Traffic jams clogged the roads out of some cities, and some walked on foot into Poland and Hungary.

The UN refugee chief warned that the humanitarian impact will be "devastating".

"We are particularly worried about displacement - about people on the move," Filippo Grandi told the BBC's Lyse Doucet, who is in Kyiv.

Explosions have already been heard in Kyiv, Kharkiv and in the Belgorod province of Russia.

Explosions also rocked the breakaway eastern Ukrainian city of Donetsk and civilian aircraft were warned away as the United States said a major attack by Russia was imminent.

Putin made the declaration in a televised speech at the same time as the UN Security Council was imploring him to stop.

Putin says Russia does not plan to occupy Ukrainian territory.

He called on Ukrainian soldiers to immediately lay down their weapons and go home.

It's reported to be part of what Ukrainian officials said was an intensifying wave of hacks aimed at the country.

In a series of statements posted to Twitter, the company said that the data wiping program had been "installed on hundreds of machines in the country," an attack it said had likely been in the works for the past couple of months.

Vikram Thakur of cybersecurity firm Symantec, which is also looking into the attacks, told Reuters that infections had spread widely.

They will target specific Russian individuals and corporations "who are at the heart of this bullying and aggressive behaviour".

"The reason we're doing this is there must be a price for the unprovoked, unlawful, unwarranted, unjustified attacks and threats and intimidation that has been imposed by Russia on Ukraine," Morrison tells reporters in Sydney on Thursday.

Ukrainians currently in Australia and with visas that expire by 30 June will have them extended by six months.

The self-declared people's republics of Donetsk and Luhansk are home to Russia-backed rebels who have been fighting Ukrainian forces since 2014.

Russia's move is likely to end peace talks in the region, which has been under a tenuous ceasefire for years.

Western powers also fear it could pave the way for Russian military forces to enter Ukraine's eastern regions.

UK Prime Minister Boris Johnson said it would be "a flagrant violation of the sovereignty and integrity of Ukraine" and break international law. He said it was "a very ill omen and a very dark sign".