OSLO - Norway and Germany on Thursday signed joint declarations to increase the production of renewable energy and develop green industry, as the NATO allies seek to both cut their CO2 emissions and wean Germany from its reliance on Russian gas.

The declarations outlined steps to cooperate in the areas of hydrogen, battery technology and offshore wind, as well as carbon capture and storage, Prime Minister Jonas Gahr Stoere and German Economy Minister Robert Habeck told reporters in Oslo.

"Times are challenging in Europe because of the war in Ukraine," Stoere said.

"In the midst of the energy crisis, we see how important Norway is as a reliable supplier of gas to Europe, but we also see how crucial it is that we switch more quickly to more renewable energy."

Already Norwegian state-controlled oil firm Equinor and German utility firm RWE said earlier on Thursday they planned to develop an industrial value chain for the production and use of low-carbon hydrogen.

This would allow Germany to reduce its reliance on coal power and thus cut CO2 emissions, though the joint investments are contingent on a hydrogen pipeline, currently being examined by Equinor and partners, aimed at connecting Norway and Germany.

Norway has since last year overtaken Russia as Europe's biggest gas supplier, with Equinor the top exporter, after Russia's Gazprom cut off much of the gas on which Europe previously depended.

Germany is seeking to both green its economy and at the same time secure alternative sources of energy, away from Russian gas.

(Reporting by Nora Buli and Markus Wacket in Oslo, additional reporting by Nerijus Adomaitis in Oslo, Christoph Steitz in Frankfurt, writing by Gwladys Fouche, editing by Terje Solsvik)