Ukraine's foreign minister said Wednesday his country "badly" needed multiple launch rocket systems to match Russian firepower as he pressed Western allies for heavy weapons at the World Economic Forum in the Swiss Alps.

Foreign Minister Dmytro Kuleba said he had come to Davos at a "very difficult moment on the frontline" as fighting rages in the eastern Donbas region.

"The battle for Donbas is very much like the battles of the Second World War," Kuleba told journalists following talks with a slew of government officials and business leaders.

"Some villages and towns, they do not exist anymore," he said.

"They were all turned into rubble by Russian artillery fire, by Russian multiple launch rocket systems. It's devastating."

Russia overwhelms Ukraine in a number of heavy weapons, but the biggest imbalance is with MLRS, mobile batteries of long-range rockets, he added.

Washington and European countries have poured billions of dollars' worth of arms into Ukraine to help the country's outgunned forces beat back the better-armed Russian invaders.

But Kuleba said that the MLRS "is really the weapon that we badly need.

"Those countries who are dragging their feet with the issue of providing Ukraine with heavy weapons, they have to understand that every day they spend deciding, weighing different arguments, people get killed."

Ukraine has asked Washington for the MLRS.

Earlier, Ukrainian President Volodymyr Zelensky made his second video appearance at Davos, this time to ask the West to show more unity behind his country.

"Unity is about weapons. My question is, is there this unity in practice? I can't see it. Our huge advantage over Russia would be when we are truly united," Zelensky told a traditional "Ukraine Breakfast" event on the sidelines of the WEF.

Ukraine was grateful for support from US President Joe Biden, he said -- but resolve was lagging closer to home.

Kuleba said Ukraine was particularly outgunned when it came to multiple-launch rocket systems Kuleba said Ukraine was particularly outgunned when it came to multiple-launch rocket systems Photo: AFP / Yasuyoshi CHIBA

"We are on the European continent, and we need the support of a united Europe," he added.

Zelensky specifically named neighbouring Hungary, which has voiced opposition to a European Union-wide embargo on Russian oil, another key Ukrainian demand.

"Hungary is not as united as the rest of the EU," Zelensky said.

He also pointed to a lack of consensus over Sweden's and Finland's historic bid to join NATO, which has been called into question by Turkey.

"Is there this unity regarding the accession of Finland and Sweden to NATO? No, no. So, is there a strong joint West? No," the Ukrainian leader said.

Appearing in person at the same Davos event, Kuleba said Ukraine wanted the West to "to finally accept the idea that the ultimate goal of this war should be the victory of Ukraine.

"Even some very good friends of Ukraine who help us really a lot, they're still hesitant," Kuleba said.

Kuleba also called on the West to step up sanctions to "kill Russian exports".

"Every dollar and euro Russia makes on this trade is then invested on upholding the Putin regime and in keeping the Russian machine of war crimes running," he said.

Addressing concerns over Ukraine's inability to ship wheat and grains due to a Russian sea blockade, Kuleba told reporters Ukraine was in talks with the United Nations over the possibility of having a safe passage in the port of Odessa.

The harbour would have to be demined and Kyiv would need security guarantees that Russia would not then attack the port.

"In the end the whole story with this corridor is an issue of trust with Russia," he said, adding that Moscow had not proposed such an initiative.

"We are working with the United Nations to find a way to address this security concern."