Il Nuovo Postiglione - Street fighting in Ukraine as hundreds of thousands flee

Machine gun fire and explosions could be heard in Kharkiv in northeast Ukraine and an AFP journalist saw the wreckage of a Russian armoured vehicle smouldering and several others abandoned.

On the fourth day of an invasion by Russia that has sent shockwaves around the world, Ukrainian President Volodymyr Zelensky turned down Moscow's offer of a meeting in Belarus, which has allowed Russian troops passage to attack Ukraine.

Zelensky said Ukraine had proposed Warsaw, Bratislava, Budapest, Istanbul and Baku as possible alternative locations for any talks.

"Any other city in a country from whose territory missiles do not fly would suit us," Zelensky said.

"The past night in Ukraine was brutal," he said. "They fight against everyone. They fight against all living things -- against kindergartens, against residential buildings and even against ambulances."

Ukraine has reported 198 civilian deaths, including three children, since the invasion began.

But President Vladimir Putin has pressed ahead with the assault, defying crippling Western sanctions that have plunged Russia into pariah status.

Many NATO members are sending arms and ammunition to Ukraine and have offered humanitarian assistance, but they have said they will not intervene militarily.

NATO has also said it will for the first time deploy part of its 40,000-strong rapid response force to Eastern Europe in a move to reassure rattled countries that were once part of the Communist bloc.

A day after Berlin said it would send anti-tank weapons and Stinger missiles to Ukraine, German Chancellor Olaf Scholz said the world was in a "new era" and warned of possible "further sanctions".

In London, British Foreign Secretary Liz Truss said the conflict could last a "number of years".

- Curfew in Kyiv -

Apart from the attack on Kharkiv, located near the Russian border, Moscow also claimed it was "entirely" besieging the southern Ukrainian city of Kherson and the city of Berdyansk in the southeast.

Both are located close the Crimea peninsula, which Russia annexed from Ukraine in 2014.

Ukrainian officials also said that a gas pipeline in eastern Kharkiv and an oil depot near the capital Kyiv were targeted by Russian forces overnight.

The claims could not be independently verified.

Many Kyiv residents spent another night in shelters as Ukrainian forces said they fought off Russian "sabotage groups", but Sunday was relatively calm compared to previous days.

The city is under a blanket curfew until Monday but some residents ventured out regardless.

Out for a walk in a park, 41-year-old Flora Stepanova said staying at home watching the news all the time "will drive you crazy".

- Foreigners invited to fight -

Russia on Saturday ordered its forces to advance further into Ukraine "from all directions" but soldiers have encountered fierce resistance from Ukrainian troops, the intensity of which has likely surprised Moscow, according to Western sources.

Ukraine's army said it held the line against an assault on Kyiv, but was fighting Russian "sabotage groups" that had infiltrated the city.

"We will fight until we have liberated our country," a defiant Zelensky said in a video message on Saturday.

He also said Ukraine had "derailed" Moscow's plan to overthrow him and urged Russians to pressure Putin into stopping the conflict.

On Sunday, Ukraine's general staff said the 44-year-old leader was urging any foreigners to come to Ukraine "and fight side by side with the Ukrainians against Russian war criminals".

"There is no greater contribution which you can make for the sake of peace," the general staff said in a Facebook post, adding that the foreign fighters would form part of an "International Legion for the Territorial Defence of Ukraine".

- 'I was trembling' -

The UN Human Rights Office (OHCHR) says the conflict so far has left at least 240 civilians wounded, including 64 killed.

The UN refugee agency (UNHCR) says more than 368,000 people have fled to neighbouring countries, while over 160,000 are estimated to be displaced within Ukraine.

Pope Francis called for the "urgent" opening of humanitarian corridors for Ukraine to allow even more to leave.

AFP saw stationary queues of cars stretching for dozens of kilometres going up to Ukraine's border crossings with Poland.

"Attacks were everywhere," said Diana, 37, who fled the Ukrainian capital.

"My mother is still in Kyiv."

In neighbouring Romania, Olga, 36, was among hundreds to have crossed the Danube river with her three young children to safety.

"My husband came with us as far as the border, before returning to Kyiv to fight," she said.

Residents of the capital have sought sanctuary in subway stations and cellars and Zelensky announced a baby girl had been born on the metro.

Yulia Snitko, a pregnant 32-year-old, said she had sheltered in the basement of her Kyiv apartment block, fearing premature labour.

"It was more than one hour of huge explosions. I was trembling," she said.

- Crippling bank sanctions -

Responding to the invasion, the West said it would remove some Russian banks from the SWIFT bank messaging system, and froze central bank assets -- hitting some of Russia's global trade.

A senior US official said the measures would turn Russia into a "pariah", adding that a task force would "hunt down" Russian oligarchs' assets.

Germany had previously resisted the SWIFT removals over concerns Russia could cut off key gas supplies.

There have also been sanctions and boycotts in the cultural and sporting spheres as well as international travel, with several countries banning Russian airlines from their airspace.

The Kremlin has so far brushed off sanctions, including those targeting Putin personally, as a sign of Western impotence.

Putin has said Russia's actions are justified because it is defending Moscow-backed separatists in eastern Ukraine.

In an address to parishioners on Sunday, Russia's Orthodox Patriarch Kirill voiced his support, calling Moscow's opponents "evil forces".

The rebels have been fighting Ukrainian government forces for eight years in a conflict that has killed more than 14,000 people.

Claiming that two rebel statelets of Donetsk and Lugansk were under threat from Kyiv, Putin recognised their independence on Monday.

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F.Criscuolo--INP