Ukrainian President Volodymyr Zelensky on Thursday called on Germany to help destroy a new "Wall" Russia was erecting in Europe, as he appealed directly to Chancellor Olaf Scholz to bolster his tentative response to the invasion.

In a speech combining an appeal for fresh aid for his besieged country with criticism of Berlin's long accommodating stance toward Moscow, Zelensky recalled Germany's own triumph over its Cold War division.

"It's not a Berlin Wall -- it is a Wall in central Europe between freedom and bondage and this Wall is growing bigger with every bomb" dropped on Ukraine, Zelensky told MPs, echoing an appeal to history deployed before the US Congress Wednesday.

Appearing on a screen in his now trademark khaki T-shirt with dark circles under his eyes, Zelensky was welcomed by MPs in the Bundestag lower house with a standing ovation.

In a grave tone, he directly addressed Scholz, who faced fresh attacks from the conservative opposition for a halting stance in the crisis.

"Dear Mr Scholz, tear down this Wall," he implored, evoking US President Ronald Reagan's 1987 appeal to Soviet leader Mikhail Gorbachev at Berlin's Brandenburg Gate.

"Give Germany the leadership role that you in Germany deserve."

Zelensky coupled his flattery with a strong rebuke of Berlin's years-long reluctance to stand up to Moscow and sever its strong energy and business ties with Russia.

"We turned to you," he said. "We told you that Nord Stream (gas pipeline cooperation between Russia and Germany) was a kind of preparation for the war.

"And the answer we got was purely economic -- it is economy, economy, economy, but that was the mortar for the new Wall."

The Russian invasion of Ukraine on February 24 prompted Scholz to announce an overhaul of key planks of Germany's energy, economic and security policy -- some of them dating back to the end of World War II.

He has put the Nord Stream 2 pipeline project on ice, joined allies in imposing punishing sanctions on Russia and pledged a massive increase in defence spending while dropping a ban on arms exports to conflict zones in order to aid Ukraine.

Meanwhile the country has taken in more than 160,000 refugees fleeing the fighting in Ukraine.

Germany has also said it aims to be nearly free of Russian oil imports by the end of this year although it still remains heavily dependent on Russian gas.

Zelensky was welcomed with a standing ovation
Zelensky was welcomed with a standing ovation AFP / Tobias SCHWARZ

Scholz, in a tweet after Zelensky's speech, thanked him for his "forceful words".

"We see that Russia is continuing every day to wage its cruel war, with horrible losses," he said.

"We feel obliged to do everything we can so that diplomacy has a chance and the war can be stopped."

However, Berlin has resisted an outright halt to Russian energy imports, warning it would cause winter shortages and drive inflation, creating potential instability in Europe's top economy.

Christian Democrat Norbert Roettgen, who is calling for a total Russian energy embargo, led a chorus of conservative criticism of the government after Zelensky's speech, saying Scholz should have addressed parliament immediately afterwards.

He tweeted that the "historic moment" had been followed by "total silence -- that was undignified... a moment of collective shame".

His party colleague, Roderich Kiesewetter, called it "baffling" that parliament continued with plans to debate a national vaccine mandate rather than on Germany's Ukraine policy.

Zelensky stressed that the future of the continent was at stake in the current war and argued that governments across the West were failing to meet the moment.

"Every year politicians repeat 'never again'," the Ukrainian leader said, referring to annual Holocaust commemorations.

"And now, we see that these words simply mean nothing. A people is being destroyed in Europe," he said, noting that 108 children had been killed in his country since the start of the Russian offensive.

"Help us stop this war."

Despite his blunt criticism, Zelensky brought MPs to their feet once again after his 15-minute address.

At a Thursday evening press conference, Scholz was asked to respond to Zelensky's words.

"I would like to say that Mr Zelensky's speech today moved me very much, it was something very special," Scholz said.