"This visit comes at a time when Ukraine needs all the support it can get in its fight for freedom," Habeck told reporters in the Ukrainian capital.

"And it is a fight for freedom, that's the important thing that the world, Europe and Germany mustn't forget," he said, adding that Ukraine was "fighting for the values that define Europe".

Germany at the weekend announced it was sending an additional Patriot air defence system to Ukraine after pleas from Kyiv for its Western backers to urgently help foil Russian attacks.

Ukraine has said it is running out of weaponry to counter Russian missiles and drones as Moscow ramps up attacks on energy infrastructure.

German Chancellor Olaf Scholz on Wednesday urged fellow EU leaders to follow Berlin's lead and send more air defence systems to Ukraine.

In an interview with Focus magazine, Defence Minister Boris Pistorius said the German military was doing a lot to deliver weapons to Ukraine, giving the example of the extra Patriot system.

"We must increase deliveries directly from industry as well," he said.

He defended Scholz over his refusal to send Kyiv long-range Taurus missiles -- which Berlin fears could strike deep inside Russia -- saying that the chancellor has "initiated enormous support for Ukraine".

"One thing is certain: We are the world's second largest supporter of Ukraine, the largest in Europe, and by a clear margin," he said.

"We supply what Ukraine needs most urgently."

Habeck, who was accompanied by a business delegation in Ukraine, will hold talks with President Volodymyr Zelensky.

He will also meet with Ukrainian officials to discuss emergency aid and business ties as well as preparations for the annual Ukraine Recovery Conference to be held in Berlin in June, the German economy ministry said.

"Comprehensive support for Ukraine also includes support for a resilient energy supply and reconstruction. Private sector investment is crucial for this to succeed," Habeck was quoted as saying in a ministry statement.

The World Bank has estimated the total cost of Ukraine's reconstruction, more than two years since the start of the war, is at least $486 billion.