The operators of Nord Stream 2 warned of a loss of pressure in the pipeline on Monday afternoon. That led to Danish authorities saying ships should avoid the area near the island of Bornholm.
Then on Tuesday, the operator of Nord Stream 1 said the undersea lines had simultaneously sustained “unprecedented” damage in one day.
The Nord Stream 1 pipeline – which consists of two parallel branches – has not transported any gas since August when Russia closed it down, saying it needed maintenance.
It stretches 745 miles (1,200km) under the Baltic Sea from the Russian coast near St Petersburg to north-eastern Germany. Its twin pipeline, Nord Stream 2, was halted after Russia invaded Ukraine in February.