Ukraine's ambassador to Berlin has accused the German government of half-hearted support for Kyiv and said his country had become a victim of Germany's "shameful" energy dependence on Russia.

"It's not just Russian gas, it's oil, coal, metals, diamonds and other raw materials. We (Ukraine) have become the biggest victim of this perverted relationship. Ukrainians are paying for this failed German policy with their lives," Andrij Melnyk told Reuters on Friday.

His comments underscore a growing frustration in Kyiv with the government of German Chancellor Olaf Scholz, who has pledged support and backed some sanctions against Russia over its six-week-old invasion of Ukraine, but dragged its heels where experts believe it most counts - an energy embargo.

"This kind of hypocrisy with Russia dates back to Nord Stream 1 (gas pipeline)," said Melnyk. "Germany's huge dependence on Russia, at a time of the worst aggression since the Second World War, is shameful."

After the German government put its highly contested new gas pipeline from Russia, Nord Stream 2, on hold after the invasion, there have been calls, unheeded in Berlin, to shut down Nord Stream 1, which has funneled Russian gas to Germany since 2011.

This week, the European Union agreed to further sanctions on Russia, including a coal embargo, but that measure was watered down by Germany.

The EU Commission had initially proposed a wind-down of three months. That was extended to four months, said sources familiar with the discussions, following pressure mostly from Germany, the EU's main importer of Russian coal.

Scholz said Germany would need the full four months to implement the ban.

"Germany is as far away from giving us the support we need today as it was at the start of the war," Melnyk said. "More than 40 days later, the German political elite apparently still does not believe that Ukraine can win the war."

Pressure is mounting on Germany.

Veronika Grimm, one of the government’s chief economic experts that advises the chancellery, said Germany should harden its stance.

"Since the start of the war, due to the rocketing price of gas, we (in the EU) have paid around 20 billion euros ($22 billion) to Russia," she told Reuters. "This money has undermined the sanctions."

She said that while a gas embargo would hit the economy, it would be "difficult but manageable."

"The debate in Germany about a gas embargo is far too black and white," said Grimm. "There are a number of intermediate alternatives, such as imposing duty charges on imports."

Ukraine's Melnyk said he had failed despite repeated attempts to meet Scholz or Germany's foreign minister, Annalena Baerbock, one-to-one.

"I have been trying to make the point that Germany needs to deliver far more heavy weapons, as well as advocating our admission to the European Union. I have not been able to deliver this message personally to Baerbock and Scholz."

A government spokesperson said Scholz had been in regular contact with Ukrainian President Volodymyr Zelenskyy and that government representatives met frequently with Ukrainian officials, including the ambassador. ($1 = 0.9197 euros)