NATO will send 40,000 more troops to countries bordering Ukraine and has warned of “severe consequences” if Russia uses chemical weapons, but fell short of meeting Ukraine’s insistent requests for a no-fly zone.

At an unprecedented summit of the NATO military alliance, G7 members and European leaders in Brussels, the US and UK also expanded their blacklists of Russians targeted with sanctions.

NATO, which has already beefed up its eastern European presence, agreed to set up new combat units in Bulgaria, Romania, Hungary and Slovakia.

Ukraine’s President Volodymyr Zelensky pleaded with the alliance to provide his embattled country with “military assistance without limitations” as Russia was “using its entire arsenal” against the country.

Mr Zelensky begged for “1 per cent of all your planes, 1 per cent of all your tanks”.

“We can’t just buy those,” said Mr Zelensky in a virtual address to the summit.

“When we will have all this, it will give us, just like you, 100 per cent security.”

Meanwhile Ukraine’s forces said they had destroyed a large Russian landing support ship, the Orsk, which had landed at the port of Berdiansk on the Sea of Azov.

Video footage, which Reuters was able to confirm was filmed from inside Berdiansk, showed a column of smoke rising from a blaze at a dock and the flash of an explosion.

Two vessels, one of which appeared to have been damaged, were seen in the footage sailing out of the dock as a third ship burned.

Reuters could not confirm if it was the Orsk on fire in the film.

Russian officials did not immediately respond to requests for comment on the report that the support ship had been destroyed.

Russia said on Monday the ship had docked at Berdiansk, 70km southwest of the besieged port city of Mariupol, and the website of the Russian armed forces news outlet Zvezda underlined the port’s importance to Russian supply lines.

“Yes, it’s destroyed,” Ukraine’s Deputy Defence Minister Hanna Malyar told a video briefing when asked about the Orsk.

The ship was capable of carrying 45 armoured personnel carriers and 400 people, she said.

In a month of fighting, Ukraine has fended off what many analysts had anticipated would be a quick Russian victory.

So far, Russia has failed to capture any major city.

Its armoured columns have barely moved in weeks, stalled at the gates of the capital Kyiv and besieging cities in the east.

They have taken heavy casualties and are low on supplies.

Ukrainian officials say they are now shifting onto the offensive and have pushed back Russian forces, including north of Kyiv.

More sanctions, and Russian gold

Joe Biden said Russia should be removed from the G20 major economies as the US announced new sanctions plus $US1 billion ($1.3 billion) more in humanitarian aid for Ukraine and an offer to take in 100,000 refugees.

“My answer is yes, depends on the G20,” said Mr Biden when asked if Russia should be removed from the group.

Mr Biden also said if countries such as Indonesia and others did not agree with removing Russia, then in his view, Ukraine should be allowed to attend the meetings.

US will target 48 state-owned Russian defence companies, 328 members of the Duma, Russia’s lower parliament, and dozens of Russian elites.

The Duma as an entity was also named in the new sanctions.

G7 leaders would also restrict the Russian central bank’s use of gold in transactions.

Previously, sanctions against Russian elites, the country’s central bank and President Vladimir Putin did not affect Russia’s gold stockpile, which the country has been accumulating for several years.

Russia holds roughly $US130 billion ($174 billion) in gold reserves and the Bank of Russia announced on February 28 that it would resume the purchase of gold on the domestic precious metals market.

White House officials said on Thursday the move would further blunt Russia’s ability to use its international reserves to prop up Russia’s economy and fund its war against Ukraine.

The G7 and the European Union also announced a new effort to share information and co-ordinate responses to prevent Russia from evading the impact of sanctions that countries have levied since the February 24 invasion.

-with AAP