The European Commission proposed a gradual ban on Russian oil imports Wednesday to punish Moscow for its invasion of Ukraine, as Russian forces pounded sites to the east of the country and hit targets in the far west near the EU border.

The EU also pledged to "significantly increase" its support for Moldova, Ukraine's neighbour that has seen a series of attacks in a Moscow-backed separatist region, sparking fears it could be drawn into the conflict.

European Commission chief Ursula von der Leyen announced the bloc would "phase out Russian supply of crude oil within six months, and refined products by the end of the year".

If approved, the oil ban would be the EU's toughest move yet against Russia's strategic energy sector that helps the Kremlin finance its war, but will still not touch its huge gas exports.

Hungary and Slovakia, both hugely dependent on Russian oil, would be given more time to meet the ban under the proposed plan, which will need unanimous approval before going into effect.

The proposed new sanctions also include moves against Russia's biggest bank, Sberbank, and the targeting of Patriarch Kirill, the head of the Russian Orthodox Church.

Solidarity for Moldova 

Western allies continue to provide Kyiv with cash and weapons in a bid to force Russian President Vladimir Putin to pull back, alongside unprecedented sanctions.

But more than two months after the February 24 invasion, Russian forces continue to batter the south and east, where 21 civilians were killed and 28 wounded in a series of assaults in Donetsk on Tuesday.

Both sides on Wednesday also reported Russian strikes on key transport infrastructure around the western city of Lviv, near Poland, and Transcarpathia, a region bordering Hungary.

In neighbouring Moldova, there are fears the conflict will spill over the border.

Visiting the tiny ex-Soviet republic Wednesday, European Council President Charles Michel offered the EU's "full solidarity" and support including in the areas of logistics and cyber defence.

"This year we plan to significantly increase our support to Moldova by providing its armed forces with additional military equipment," he told a press conference with President Maia Sandu.

Ukraine has accused Russia of wanting to destabilise Moldova's separatist region of Transnistria to create a pretext for a military intervention.

No storming of Azovstal 

The war in Ukraine has killed thousands of people and displaced more than 13 million, creating the worst refugee crisis in Europe since World War II.

There was some rare good news on Tuesday with the arrival in the Ukrainian-held city of Zaporizhzhia of more than 150 civilians evacuated from the devastated southern port city of Mariupol.

Further evacuations from the city, now almost entirely under Russian control after two months of siege, were to take place Wednesday with the help of the United Nations and the Red Cross, a Mariupol mayoral adviser said.

Osnat Lubrani, UN humanitarian coordinator for Ukraine, had earlier said that 101 of the civilians had been evacuated from the immense underground galleries of the Azovstal steelworks, but more could be trapped.

The Russian army said Tuesday that its forces and pro-Moscow separatists were attacking "firing positions" in Azovstal where Ukrainian fighters are making their last stand.

But Kremlin spokesman Dmitry Peskov on Wednesday denied Ukrainian claims that it had launched a "powerful assault", telling reporters: "There is no storming."

"The order was publicly given by the supreme commander-in-chief to cancel the assault," he said, referring to an order given by Putin last month not to pursue an attack on the area.

Bombing every second 

Azovstal evacuees who emerged from a caravan of white buses in Zaporizhzhia were met at a makeshift reception centre by crying loved ones and dozens of journalists.

"We are so thankful for everyone who helped us. There was a moment we lost hope, we thought everyone forgot about us," evacuee Anna Zaitseva said, holding her six-month-old baby in her arms.

Elyna Tsybulchenko, 54, who worked at the site doing quality control before the war trapped her there, described days and nights of endless barrages.

"They bombed like every second... everything was shaking. Dogs barked and children screamed," she told AFP. "But the hardest moment was when we were told our bunker would not survive a direct hit."

No safe place

Since abandoning early attempts to capture Ukraine's capital Kyiv, Russian forces have shifted to the east, including largely Russian-speaking areas, and the south.

Ukraine's general staff said Wednesday the Russian assault continued with the aim of establishing "full control" of the regions of Lugansk and Donetsk, and to maintain a land corridor to occupied Crimea.

Russia's defence ministry said Wednesday that its air- and sea-based weapons had destroyed six electrical substations near railways including around Lviv, near Odessa to the south, and near Dnipropetrovsk to the south-east.

It said Ukrainian troops in the eastern Donbas region had used the railway stations to transport weapons and ammunition from the EU and United States.

Meanwhile in the eastern Lugansk region, governor Sergiy Gaiday said two people had died in the last 24 hours, and "the whole region is under fire completely, there is no safe place".

Battle for democracy 

US President Joe Biden on Tuesday framed the war as a historic battle for democracy in a speech to workers at a factory producing Javelin missiles, which have wreaked havoc on Russian tanks.

Reprising one of his presidency's core themes, Biden said the fight by democratic Ukraine against Putin's Russia was a front in a wider contest between democracies and autocracies worldwide, including China.

Chinese leader Xi Jinping had told him that democracies can no longer "keep up," Biden said.

Ukraine is the "first" battle "to determine whether that's going to happen," he said.

Elsewhere, diplomats said Russia will boycott a UN Security Council meeting Wednesday with the EU's Political and Security Committee (PSC), a further sign of deteriorating relations between Moscow and its United Nations partners.