The city of Berlin started switching off spotlights illuminating its historic monuments as part of a national effort to save energy in the face of Russian gas shortages.

Some 200 buildings and landmarks including Berlin's red-brick city hall, State Opera House and Charlottenburg Palace will fall dark at night, officials in the German capital said this week.

"Given the war against Ukraine and the energy policy threats by Russia, it's important that we be as careful as possible with our energy," the city's chief official for the environment, Bettina Jarasch, said on Wednesday.

Jarasch of the Green party said that included consumers and industry but also public institutions, calling the move "the right thing to do to make a visible contribution".

The policy affected six monuments from Wednesday night and will eventually encompass 200 buildings and landmarks along with their 1,400 spotlights over the next four weeks, Jarasch's office said.

An electrical services firm will shut off 100-120 lights per day without dismantling them, keeping the policy temporary.

The cash-strapped capital will not save money as the labour costs are expected to match the benefit of cutting energy use.

President Frank-Walter Steinmeier said this week he wanted to set an example by keeping the facade of his official residence, Bellevue Palace in Berlin's sprawling Tiergarten park, dark at night.

Berlin's city hall is one of the landmarks that will fall in darkness at night
Berlin's city hall is one of the landmarks that will fall in darkness at night AFP / John MACDOUGALL

Several German cities have said they would step up efforts to limit the use of energy, with Hanover in the north announcing plans this week to only offer cold showers at public pools and sports centres.

Chancellor Olaf Scholz's centre-left-led government has launched a national drive to save energy amid soaring prices due to the Russian invasion of Ukraine, and the EU agreed this week to reduce Russian gas use across the bloc.

Officials have warned that the Kremlin could cut off supplies this winter in retaliation for biting Western sanctions against Moscow over the war.

The German efforts include reducing the use of air conditioning, promoting public transport and pushing for more efficient shower heads.

Before the Ukraine war, Germany bought 55 percent of its natural gas from Russia.

Although the rate had fallen to 35 percent by early June, Europe's top economy is still heavily dependent on Russia for its energy, and says Moscow is using it as a "weapon".

On Wednesday, Russian state-run energy giant Gazprom slashed deliveries of gas through the Nord Stream pipeline to Germany to 20 percent capacity from the previous 40 percent.