Uniper, Germany's largest gas trader, in November 2022 initiated arbitration proceedings against Gazprom before an international tribunal, asking for compensation for suspended gas deliveries.

Gazprom in 2022 first cut and later fully suspended supplies via the Nord Stream pipeline, which was sabotaged, forcing Uniper to buy gas at sky-high prices on the spot market to fulfil its contracts.

As a result Germany had to step in to prevent the company from collapsing.

"We expect a decision in the summer," Uniper Chief Executive Michael Lewis told journalists late on Tuesday, adding the case was worth "many billions of euros".

Turning to Germany's energy policy, Lewis criticised Berlin for not delivering a so-called power plant strategy that aims to provide a clear framework of incentives for new gas-fired power stations, needed to close the gap that emerges due to Germany's phase-out of coal.

Lewis said nobody would invest in new capacity without a clear regulatory roadmap, adding the fact that the government had not delivered its strategy, first announced last year, was "very frustrating".

The German Economy Ministry said that the government's internal preparations were still ongoing and that the strategy was to be presented soon.

(Reporting by Tom Kaeckenhoff and Markus Wacket; Writing by Christoph Steitz, Editing by Linda Pasquini and Chizu Nomiyama)