MOSCOW/KYIV: Russian President Vladimir Putin on Friday called on the Ukrainian army to overthrow the government whose leaders he described as "terrorists" and "a gang of drug addicts and neo-Nazis".

Putin also accused "Ukrainian nationalists" of deploying heavy weapons in residential areas of major cities to provoke the Russian military, a claim that could fuel fears Moscow is creating pretexts for justifying civilian casualties.

In a televised address, he urged the Ukrainian military to "take power in your own hands".

"It seems like it will be easier for us to agree with you than this gang of drug addicts and neo-Nazis," he said, referring to the leadership in Kyiv under President Volodymyr Zelensky, who is Jewish.

Putin, who on Thursday ordered Russian troops to invade Ukraine, claimed that Ukrainian "nationalists" were preparing to deploy multiple rocket launchers to residential areas of Ukrainian cities, including Kyiv and the northeastern city of Kharkiv.

Ukraine's leadership are "acting like terrorists all over the world: they are hiding behind people in the hope of then blaming Russia for civilian casualties".

"It is known for a fact that this is happening on the recommendation of foreign consultants, primarily American advisers," Putin said.

Separately, Putin's spokesman Dmitry Peskov said of the alleged deployment: "We consider the situation to be extremely dangerous."

Putin and top Russian officials have said Moscow's troops are only targeting ultra-nationalists in Ukraine.

Putin also praised Russian troops saying they were acting in a "courageous and professional manner".

"They are successfully solving the most important task of ensuring the security of our people and our Fatherland," Putin said.

On a conference call to reporters, Peskov accused the Ukrainian authorities of refusing to hold talks with Russians in Belarus, as was previously suggested by Moscow.

"After a brief pause Ukrainians said they now want to go to Warsaw," Peskov said. "And now they have gone incommunicado."

Earlier updates

Meanwhile, Russian forces are approaching Kyiv from the north and northeast, Ukraine's army said, with rising fears the capital could fall on the second day of Moscow's offensive.

The soldiers are trying to "bypass" the northern city of Chernigiv – where they were "rebuffed" – to attack Kyiv, the Ukrainian army said on Facebook.

They were also advancing on Kyiv from the eastern city of Konotop, which is under Russian control, Kyiv's army said.

The Ukrainian army earlier said Russian ground forces had been pushing down the west bank of the Dnieper River from Belarus.

It said Russian soldiers were "increasingly choosing to target civilian infrastructure and residential buildings", echoing President Volodymyr Zelensky.

An AFP reporter heard explosions and gunfire erupting in the northern part of Kyiv on Friday, with people running for safety in the city's Obolonsky area.

Moscow's forces arrived on the outskirts of Kyiv on Thursday when helicopter-borne troops attacked an airfield just outside the city, near Obolonsky.

The Ukrainian army said Friday it was fighting Russian forces north of the capital in the villages of Dymer -- around 45 kilometres (28 miles) from Kyiv -- and Ivankiv, about 60 kilometres northwest of the city.

The military claimed to have stopped advancing forces at the Teteriv River outside Kyiv, adding that it had repulsed an attack on the Gostomel airbase.

As Moscow forces arrived in Obolonsky, within the city, the defence ministry urged civilians to resist.

"We urge citizens to inform us of troop movements, to make Molotov cocktails, and neutralise the enemy," it said.

Russian President Vladimir Putin announced he was launching a major military operation in Ukraine in the early hours of Thursday.

Western countries have imposed a barrage of international sanctions against Russia since then.

Earlier updates

Earlier, Ukrainian forces fought off Russian troops in the streets of the capital Kyiv as President Volodymyr Zelensky accused Moscow of targeting civilians and called for more international sanctions.

Pre-dawn blasts in Kyiv set off a second day of violence after Putin defied Western warnings to unleash a full-scale invasion on Thursday that quickly claimed dozens of lives and displaced at least 100,000 people.

The United States and its allies responded with a barrage of sanctions, but the Russian forces looked to press home their advantage after a string of key strategic victories in their air and ground assault.

Zelensky recalled Nazi Germany's 1941 invasion and praised his people for "demonstrating heroism".

As Russian forces closed in on the city, Zelensky called on Europeans with "combat experience" to take arms and defend Ukraine, saying the West was too slow to help his country.

Russian Foreign Minister Sergei Lavrov said Moscow wanted to "free Ukraine from oppression" and denied there had been any strikes on civilian targets.

He said Moscow was ready to talk if Ukraine's armed forces "lay down their arms", adding that "nobody intends to occupy Ukraine".

Trail of destruction

In Obolonsky, a northern district of Kyiv, what appeared to be an advance party of Russia's invasion force left a trail of destruction.

Pedestrians ran for safety and small arms fire and explosions were heard.

A dead man in civilian clothes lay sprawled on the sidewalk and, nearby, medics rushed to help another man whose car was crushed under the tracks of an armoured vehicle.

In contrast, the city centre felt like a ghost town.

Intersections around the government district were manned by green armoured vehicles and machine-gun toting soldiers in balaclavas.

Sirens wailed over the cloudy city at jarring intervals throughout the day. Booms of unexplained origin echoed across the deserted streets.

Russian forces first arrived on the outskirts of Kyiv on Thursday when helicopter-borne troops assaulted an airfield just outside the city, close to Obolonsky.

Ukraine said more forces were advancing from the north and northeast of the city.

As Russian forces arrived in Obolonsky, the Ukrainian defence ministry told civilians to resist.

"We urge citizens to inform us of troop movements, to make Molotov cocktails, and neutralise the enemy," it said.

Ukraine says 137 people, including soldiers and civilians, have been killed since Russia attacked.

After speaking to EU chief Ursula von der Leyen, Zelensky called for more sanctions, tweeting that "the pressure on Russia must increase".

'Better to die'

In the Ukrainian village of Starognativka near the frontline where separatists have faced off against Kyiv's forces for years, official Volodymyr Veselkin said on Friday missiles had been raining down all morning and the power was out.

"They are trying to wipe the village off the face of the earth," he said.

The UN's refugee agency said late Thursday that some 100,000 were already displaced inside Ukraine, while thousands of others fled across the border.

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

In Kyiv, many residents fled their homes and took shelter in the city's subway system.

Zelensky said there was now a "new iron curtain" between Russia and the rest of the world, adding later that his nation had been "left alone".

"Who is ready to fight alongside us? I don't see anyone."

And while the United States moved to impose sanctions on Russian elites and banks, it stressed that American forces would not fight in Ukraine.

NATO also said it would not send forces to Ukraine.

Among the highest-profile strategic developments on Thursday, Ukraine said Russian forces had seized the Chernobyl nuclear power plant -- prompting concern from international nuclear watchdogs.

Zelensky called the attack on Chernobyl "a declaration of war on all of Europe".

Russia said Thursday its forces had destroyed over 70 Ukrainian military targets, including 11 airfields.

Western intelligence confirmed Moscow had established "complete air superiority" over Ukraine.

Sanctions

Weeks of diplomacy failed to deter Putin, who massed over 150,000 troops on Ukraine's borders in what the West said was Europe's biggest military build-up since World War II.

Western allies had initially imposed some sanctions on Russia in an effort to stop Putin from invading, then followed through on Thursday with vows to heavily punish Russia economically.

US President Joe Biden announced export controls against Russia, alongside sanctions on Russian elites he called "corrupt billionaires", and banks.

He will meet Friday with fellow NATO leaders in an extraordinary virtual summit to discuss the security situation in and around Ukraine.

The EU moved to impose "massive" sanctions on Russia's energy and finance sectors and promised to adopt more.

A rare voice of support for Moscow came from the Myanmar junta which said Russia's invasion of Ukraine was "justified", while Syrian President Bashar al-Assad praised the invasion, saying it was a "correction of history".

Demonstrations across Europe

In a televised address, Putin justified the assault as a defence of the self-proclaimed Donetsk and Lugansk republics in eastern Ukraine.

The leaders of the two separatist territories asked Moscow for military help against Kyiv after Putin recognised their independence on Monday.

A conflict between the separatists and government forces has dragged on since 2014, killing more than 14,000 people.

Russia has also long demanded that Ukraine be forbidden from ever joining NATO and that US troops pull out from Eastern Europe.