Russian artillery bombarded residential districts of Ukraine's second largest city Kharkiv on Monday, killing possibly dozens of people, Ukrainian officials said, as Moscow's invading forces met stiff resistance from Ukrainians on a fifth day of conflict.

The attacks took place while Russian and Ukrainian officials met on the Belarusian border to discuss a ceasefire. The talks ended with no breakthrough.

Russia also faced deepening isolation and economic turmoil as Western nations, united in condemnation of its assault, hit it with an array of sanctions that created ripple effects around the world. Global shares slid and oil prices jumped.

But Russian President Vladimir Putin showed no sign he was reconsidering the invasion he unleashed on Russia's western neighbour last Thursday. He dismissed the West as an “empire of lies” and replied to the new sanctions with moves to shore up Russia's crumbling currency.

The Russian invasion — the biggest assault on a European state since World War Two — has failed to make the decisive early gains that Putin would have hoped for. But Kharkiv in Ukraine's northeast has become a major battleground.

Regional administration chief Oleg Synegubov said Russian artillery had pounded residential districts even though no Ukrainian army positions or strategic infrastructure were there. At least 11 people had been killed, he said.

“This is happening in the daytime, when people have gone out to the pharmacy, for groceries, or for drinking water. It's a crime,” he said.

Earlier, Interior Ministry adviser Anton Herashchenko said Russian rocket strikes on Kharkiv on Monday had killed dozens of people. It was not possible to independently verify the casualty figures.

Video posted by the military showed thick columns of smoke rising from apartment blocks and flashes of flames.

Moscow's United Nations ambassador, speaking in New York, said the Russian army did not pose a threat to civilians.

Fighting also occurred throughout the night around the port city of Mariupol, the head of the Donetsk regional administration, Pavlo Kyrylenko, said. He did not say whether Russian forces had gained or lost ground.

Russian forces seized two small cities in southeastern Ukraine and the area around a nuclear power plant, according to the Interfax news agency.

The capital Kyiv remained under Ukrainian government control, with President Volodymyr Zelenskiy, dressed in military gear, encouraging his people with a series of defiant messages.

Explosions were heard in the city before dawn and Ukrainians set up checkpoints and blocked streets with piles of sandbags and tyres as they waited to take on Russian soldiers.

On Kyiv's streets, signboards normally used for traffic alerts showed the message: “Putin lost the war. The whole world is with Ukraine.”

Talks on border

Talks between the two sides took place on the border with strong Russian ally Belarus — a launch pad for invading Russian troops.

Ukraine had said it wanted to secure an immediate ceasefire and the withdrawal of Russian forces. The Kremlin declined to comment on Moscow's goals.

The meeting ended with officials heading back to their respective capitals for further consultations before a second round of negotiations, RIA news agency quoted Ukrainian presidential adviser Mykhailo Podolyak as saying.

Russia calls its actions in Ukraine a “special operation” that it says is not designed to occupy territory but to destroy its southern neighbour's military capabilities and capture what it regards as dangerous nationalists.

The Western-led response has been emphatic, with sanctions that effectively cut off Moscow's major financial institutions from Western markets.

The rouble plunged 32 per cent against the dollar on Monday before recouping about half of its losses. Countries also stepped up weapons supplies to Ukraine.

In Brussels, European Union foreign policy chief Josep Borrell said EU sanctions would have a cost for Europe “but we have to be ready to pay the price, or we will have to pay a much higher price in the future”.

The EU will provide intelligence to Ukraine about Russian troop movements and EU countries are determined to increase their military support to Kyiv, Borrell said.

France said President Emmanuel Macron spoke to Putin on Monday and urged an immediate ceasefire and an end to attacks on civilians and infrastructure.

Battle for cities

The Ukrainian military said Russian forces were also focusing on Chernihiv, northeast of Kyiv, and parts of the Donetsk region in the east. Separatists there raised a Russian flag on a local administration building in one shattered village on Sunday, Reuters footage showed.

UN human rights chief Michelle Bachelet said at least 102 civilians in Ukraine have been killed since Thursday but the real figure is feared to be “considerably higher”.

Ukraine's health ministry said on Sunday 352 civilians, including 14 children, had been killed since the beginning of the invasion.

More than half a million people have fled to neighbouring countries, according to the United Nations refugee agency.

Partners in the US-led Nato defence alliance were providing Ukraine with air-defence missiles and anti-tank weapons, NATO chief Jens Stoltenberg said.

The Kremlin accused the EU of hostile behaviour, saying weapons supplies to Ukraine were destabilising and proved that Russia was right in its efforts to demilitarise its neighbour.

The Kremlin declined to comment on whether there was a risk of confrontation between Russia and Nato. Russia has demanded that Nato never admit Ukraine as a member.

Over the weekend, Western nations announced sanctions including barring some Russian banks from the SWIFT international payments system.

In an emergency move, Russia's central bank raised its key interest rate to 20 per cent from 9.5pc as the rouble dived. Authorities told export-focused companies to be ready to sell foreign currency.

The bank also ordered brokers to block attempt by foreigners to sell Russian securities.

Corporate giants took action in response to the sanctions, with BP, the biggest foreign investor in Russia, saying it would abandon its stake in state oil company Rosneft at a cost of up to $25 billion.