Europe was investigating Tuesday what Germany, Denmark and Sweden said were attacks that had caused major leaks into the Baltic Sea from two Russian gas pipelines at the center of an energy standoff.

But it remained far from clear who might be behind the leaks that were first reported on Monday or any foul play, if proven, on the Nord Stream pipelines that Russia and European partners spent billions of dollars building.

German Economy Minister Robert Habeck told business leaders the leaks were due to targeted attacks on the infrastructure and that Berlin now knew for sure "they were not caused by natural occurrences or events or material fatigue."