Zelensky calls on Ukrainians to resist

The Ukrainian president called on citizens to persevere as Russian forces advanced into the suburbs of Kiev but met fierce resistance that has so far prevented them from taking one of the country's largest cities.

Russian President Vladimir Putin had earlier called on the Ukrainian army to mutiny to spare the nation bloodshed as he expanded his assault and moved a third of Russia's total forces into the country, according to US estimates.

Nato member states, meanwhile, pledged to continue supplying Ukraine with military weapons, including air defence systems. "We are in this for the long haul," Nato Secretary General Jens Stoltenberg said after an emergency meeting of the alliance.

The US, EU and UK also imposed direct sanctions on Putin and Russian Foreign Minister Sergei Lavrov - a rare instance of such measures being imposed on a foreign leader.

While Ukrainian citizens huddled in bunkers, fled or armed themselves with makeshift weapons, President Volodymyr Zelensky appeared on television shortly before midnight local time on Friday and called on them to fight.

"Tonight the enemy will use all the forces at his disposal to break our resistance," Zelensky said, hours after warning that Russian saboteurs had entered the capital and were trying to kill him. "We have to hold out tonight. The fate of Ukraine is being decided right now."

There were loud explosions in Kiev on Friday and reports of Russian armoured vehicles advancing into the northern Obolon district, bringing street fighting to the capital of 3 million.

Western officials, however, said the tenacious Ukrainian opposition had slowed Russia's attempt to encircle Kiev and take Kharkiv in the northeast, the country's second-largest city.

The battlefield setbacks highlighted the challenge Putin still faces after pitting Europe's largest invasion force in half a century against an outgunned but determined Ukrainian military that appears poised to hold its own in the urban war.

"In general, the Russians have lost a little of their momentum," a Pentagon official said. "A good sign is that no population centres have been taken.

As Russian tank columns moved to encircle Kiev, Putin urged Ukrainian forces to "take power into their own hands" and overthrow their government so they could reach a peace deal with Russia.

In a post on social media on Friday evening, a spokesman for the Ukrainian president said they had started talks with the Russians about a possible "negotiation process". However, it was not clear whether the suggestion of talks was realistic given Russia's extreme demands.

Air raid sirens sounded in the capital and authorities warned people to seek shelter in shelters or metro stations in the face of Russian bombardment. According to the Pentagon, Russia has fired 200 ballistic and cruise missiles so far during the invasion.

The exodus of civilians from Kiev continued. Traffic was heavy on the roads leading out of the capital, and some residents fled the centre on foot with suitcases, hoping to be picked up by passing cars.

The Ukrainian military called on Obolon residents to inform them that Russian equipment was being moved into the city. "Make Molotov cocktails, neutralise the occupier," the defence ministry said.

Russia claimed on Friday to have seized Kyiv's Hostomel airport near the Obolon district after it changed hands several times on Thursday in fighting involving special forces, attack helicopters and precision-guided missiles.

Control of the runway could allow Russia to quickly deploy large numbers of troops directly to the capital.

According to US officials, Russia has ordered thousands more combat troops into Ukraine, including through amphibious assaults near Mariupol in the Sea of Azov.

Ukrainian forces destroyed bridges north of the city overnight to impede the Russian advance. Western military officials warned that the arrival of tens of thousands of troops advancing south from Belarus and north from Crimea would bring "overwhelming" military superiority that could lead to the capital falling within days.

"They are fighting back and not doing badly, but they are still overwhelmed," a senior Western intelligence official said. "I have no doubt that they will fight as long as they can.

Earlier on Friday, Ukraine's defence ministry said its forces had shot down more than a dozen Russian planes and helicopters, as well as numerous tanks and armoured vehicles. Zelensky said 137 of his compatriots were killed. Russia did not give details of damage to its military facilities or casualties.

Ben Wallace, Britain's defence secretary, said intelligence estimates showed Russia had lost more than 450 men on the first day of operations, taking "none of its main targets".

While videos on social media show both sides have suffered battlefield casualties since Thursday, the exact figures provided by the Russian, Ukrainian and Nato militaries cannot be independently verified.

Shocked world leaders condemned what they said was the biggest challenge to Europe's post-war order in 80 years. "Putin has much bigger ambitions than Ukraine," US President Joe Biden said on Thursday. "He does indeed want to restore the former Soviet Union. That's what this is all about."

Zelensky thanked Western leaders for their support but questioned their willingness to go further. "Who is ready to fight with us? Honestly, I don't see anyone.... I ask them, are you on our side?"

Nato held an emergency summit of its 30-member heads of state and government on Friday to discuss the invasion.

Oil prices steadied on Friday after topping $100 a barrel on Thursday for the first time since 2014. Oil prices had risen as high as $106 before falling back after the Biden administration announced a series of sanctions focused on Russia's financial sector rather than energy.

European natural gas prices fell back after surging nearly 70 percent to 142 euros per megawatt hour on Thursday. Futures linked to the TTF, the European wholesale gas price, fell more than 30 per cent to 92.50 euros on Friday.

European stocks recovered their losses from the previous day. US stock markets also rose, and the S&P 500 ended the day up more than 2 per cent.