German Foreign Minister Johann Wadephul has arrived in Ukraine on a solidarity visit just days before the country marks the 35th anniversary of its independence, as Russia steps up its military assault on the country.

Wadephul arrived by special train at Kiev's main railway station early on Saturday and condemned Russia's escalating drone and missile strikes, accusing Moscow of the "indiscriminate murder of civilians" and the deliberate destruction of energy infrastructure.

The visit comes days after 16 people were killed in Russian missile strikes on the Ukrainian capital, and one day after a separate attack on a shopping centre in President Volodymyr Zelensky's home city of Kryvyi Rih left at least 15 dead and 130 hurt.

Wadephul said Russia was trying to destroy the livelihoods of the Ukrainian population and break their will to resist.

The summer months of July and August have been the deadliest for the Ukrainian civilian population in more than four years, he said.

"Never before has Russia fired more missiles at its neighbouring country," Wadephul said. "We see the suffering, we see how this country has struggled, and we will continue to support this country."

"We stand on Ukraine's side," he added. "It will win this military confrontation."

The German foreign minister pledged further support for Ukraine as it prepares for a fifth winter of war since Russia's invasion in February 2022, with further attacks on its energy infrastructure expected.

"No country invests as much in military and financial support for Ukraine as Germany," Wadephul said, expressing hope that Russia could be brought to the negotiating table even as diplomatic efforts have stalled in recent months.

Ukraine has stepped up its assault on Russia's oil facilities and logistics centres this year, aiming to damage Moscow's war economy with drone strikes deep in the Russian interior.

However, a shortage of air defence units such as Patriot missiles has left the country defenceless against Russian missile strikes, leading Zelensky to plead for more support from Ukraine's Western partners.

The visit was Wadephul's fourth to Ukraine since taking office 16 months ago. It was not announced publicly in advance for security reasons, as is customary.

His programme in Kiev has also not been disclosed, though talks with the Ukrainian leadership are expected to be the focus.

Ukraine declared independence from the Soviet Union 35 years ago on Monday. Celebrations are taking place around the anniversary, primarily in the capital Kiev.

FILE PHOTO - German Minister of Foreign Affairs Johann Wadephul speaks during a press conference with Swiss head of the Federal Department of Foreign Affairs Ignazio Cassis after their meeting. (is associated with: «German foreign minister visits Kiev as Russia steps up missile attacks») Lilli Förter/dpa
FILE PHOTO - German Minister of Foreign Affairs Johann Wadephul speaks during a press conference with Swiss head of the Federal Department of Foreign Affairs Ignazio Cassis after their meeting. (is associated with: «German foreign minister visits Kiev as Russia steps up missile attacks») Lilli Förter/dpa