Berlin: Prime Minister Denys Shmygal will be the first high-level Ukrainian official to visit Germany in months on Sunday, in a sign of eased tensions after a rocky patch between Kyiv and Berlin.

Chancellor Olaf Scholz has repeatedly vowed Germany's strong support for Ukraine in its battle against Russia's invasion.

But in the immediate weeks after Russian troops marched on Ukraine, Kyiv had blasted German aid as too little and too late.

A visit by Scholz to Kyiv in June and the arrival of weapons from Germany have since led to a change in tone.

"Germany has made huge progress in its support of Ukraine with weapons," Shmygal told German media ahead of his trip, in a transcript published by his press office.

But the prime minister said Kyiv needs more from Berlin, including "modern combat tanks" like the Leopard 2.

Scholz will welcome Shmygal with military honours in the afternoon.

But Shmygal will be starting his day with talks on Sunday morning with German President Frank-Walter Steinmeier, whose offer to travel to Kyiv in April was rebuffed, sparking a row.

Steinmeier, a former foreign minister from Scholz's Social Democratic Party, had been shunned over his years-long detente policy towards Moscow -- something which he has admitted was a mistake following the outbreak of war.

- 'Special responsibility' -

Germany's SPD has historically championed close ties with Russia, born out of the "Ostpolitik" policy of rapprochement and dialogue with the then Soviet Union, devised by former SPD chancellor Willy Brandt in the 1970s.

That tradition had led in part to Germany initially refusing any weapons deliveries to Kyiv, with a previous decision to send only 5,000 helmets sparking anger and mockery.

But Scholz's coalition, which also includes the Greens and liberal FDP, has since made a sharp U-turn.

Howitzers, rocket launchers and anti-aircraft missiles are among the weapons that have arrived in Kyiv.

Heavier weapons like the IRIS-T anti-aircraft systems, rocket launchers mounted on pick-ups and anti-drone equipment are due in a further military aid package worth over 500 million euros.

And Ukrainian soldiers are currently being trained in Germany to use the anti-aircraft Leopard tanks.

In a speech on his vision for Europe on Monday, Scholz said he saw Germany taking on "special responsibility" to help Ukraine build up its artillery and air defence systems.

Germany, he added, will maintain its backing for Ukraine for "as long as it takes".

On the humanitarian level, Germany has taken in almost a million Ukrainian refugees, with some 155,000 Ukrainian children now enrolled in German schools.

Ahead of Shmygal's trip, Scholz's coalition partner the Greens, traditionally known as pacifists, said Germany wants to "boost" its armament deliveries to Ukraine.

"Military means never bring the solution, but it sometimes creates windows of opportunities in which conflicts can be politically resolved in a rules-based world order," the party's leadership said in a motion put forward for consideration at its next congress.