Germany said Saturday it will send an additional Patriot air defence system to Ukraine to bolster its hard-pressed military and help it fend off increased Russian aerial attacks.

"Russian terror against Ukrainian cities and the country's infrastructure is causing immeasurable suffering," said German Defence Minister Boris Pistorius, announcing the move.

"It is jeopardising people's energy supply and destroying the operational readiness of the Ukrainian armed forces."

It will be the third Patriot system that Berlin has supplied to Kyiv, with the defence ministry saying the decision was taken at the request of the Ukrainian government and in coordination with allies.

Chancellor Olaf Scholz also spoke by phone with Ukrainian President Volodymyr Zelensky Saturday, reaffirming his "unwavering solidarity with Ukraine in the face of massive and ongoing Russian airstrikes, particularly on civilian energy infrastructure," a German government spokesman said.

As well as discussing Germany's delivery of a new Patriot system, Scholz and Zelensky agreed that "further efforts by partners are also required" to boost Ukraine's air defence, the spokesman said.

The announcement comes as Kyiv struggles on the battlefield against Moscow's forces, hobbled by a lack of foreign aid, as well as a shortage of men and ammunition.

Russia has been stepping up aerial attacks on Ukraine. On Thursday Moscow pounded the country's energy facilities, destroying a power station in the Kyiv region.

After the outbreak of the Ukraine war in 2022, Germany dropped a traditionally pacifist stance and has become Ukraine's second-biggest supplier of military aid, after the United States.

However, a key package of US aid for Kyiv has been held up due to political squabbling in Congress.

As well as Patriots, Berlin has supplied a wide array of other armaments, ranging from artillery to armoured fighting vehicles.

The defence ministry said the handover of the new Patriot system from German military stocks would begin immediately.

Despite Germany delivering billions of euros of military supplies to Ukraine, Chancellor Olaf Scholz has come under fire in recent months for refusing to allow the supply of long-range Taurus missiles.

Germany fears the missiles could be used to hit targets deep within Russia.