Frustration is growing among German Chancellor Olaf Scholz's junior coalition partners over what they say are shortcomings in his leadership on Ukraine, an internal rift that risks undermining Western unity against Russia.

After a dramatic policy pivot at the start of the crisis, when Scholz halted the Nord Stream 2 gas pipeline project with Russia days before its invasion of Ukraine, and then vowed a big jump in defence spending, his partners accuse him of dithering.

"I have the impression that Mr Scholz is not aware of the serious damage he is doing to Germany's reputation in Central Europe, in Eastern Europe, basically in the whole of Europe," Anton Hofreiter, Greens chairman of parliament's Europe committee, told Reuters.

Seven weeks into the war, the junior Greens and liberal Free Democratic (FDP) parties in Scholz's coalition are vexed that Berlin is not meeting Ukrainian pleas to send it more heavy weapons, amid warnings from Kyiv that Russia is ramping up for a major offensive in Ukraine's south and east.

Some in the three-way coalition with Scholz's left-leaning Social Democratic Party (SPD) also want him to do more to reduce German energy dependence on Russia.

"He must finally show leadership," Hofreiter said.

Last week, Ukraine's ambassador to Berlin accused the German government of half-hearted support for Kyiv and said his country had become a victim of Germany's "shameful" reliance on Russian oil and gas. He also demanded more heavy weapons.

When asked by rbb24 Inforadio on Wednesday whether he was showing leadership, Scholz replied: "Certainly..., and quite a bit."

Government sources said the softly spoken chancellor sees it as part of his role to hold together the heterogeneous coalition of his SPD, the Greens and FDP, and that he is not much bothered by short-term dips in popularity and does not react to them.

Scholz also said in the radio interview that Berlin was sending Ukraine anti-tank weapons, air defence missiles and other arms. He added quickly: "We will make sure to avoid NATO, the NATO countries and...Germany becoming parties to the war."

BALANCING ACT

Scholz must balance pressure from the Greens in particular to step up arms supplies to Ukraine with some reticence in elements of his SPD, which long advocated Western rapprochement with Russia prior to the war in Ukraine.

Underlining the Greens' robust stance, Foreign Minister Annalena Baerbock, a member of the ecologist party, called this week for the delivery of more heavy weapons, adding: "Now is not the time for excuses, but for creativity and pragmatism."

Hofreiter went further and called for a coal and oil embargo against Russia "as a minimum".

The European Union last Friday overcame some divisions to adopt new sweeping sanctions against Russia, including bans on the import of coal, wood, and chemicals.

However, oil and gas imports from Russia - the financial lifeline of its war machine, critics say - so far remain untouched, with Berlin leading resistance to the move.

Germany, Europe's largest and wealthiest economy, gets about 25% of its oil and 40% of its gas from Russia. Russian gas accounts for 40% of overall EU imports of that energy source.

"I am of the opinion that even a complete energy embargo is possible," said Hofreiter, who visited Ukraine this week with the SPD's Michael Roth and the FDP's Marie-Agnes Strack-Zimmermann, the chairs of parliament's foreign relations and defence committees respectively.

Mujtaba Rahman, Managing Director, Europe at the Eurasia political risk consultancy, expects Germany will ultimately buckle on oil sanctions lest the West's unity break.

"The cracks are really beginning to show in the coalition, but the top and bottom of it is (that) Germany's policy on Russia and Ukraine is entirely unsustainable," he said in an email to Reuters. "On oil sanctions, on EU fiscal support, the position of Berlin will be forced to evolve."

(Additional reporting by Reuters TV and Andreas Rinke Editing by Mark Heinrich)