The US Central Intelligence Agency (CIA) warned the German government there would be attacks on Nord Stream gas pipelines weeks ahead of any incident being reported around the pipelines, German newspaper Der Spiegel reported Tuesday.

An informed source told the German newspaper that Berlin had been informed by the CIA a few weeks ago that there would be attacks on the key pipelines supplying a huge portion of Europe's energy from Russia.

The media outlet cited several unnamed individuals as confirming that the CIA tipped the German government about the incident that was yet to take place.

"As a matter of principle, we do not take a public position on matters relating to any intelligence findings or activities of the intelligence services," a German spokesperson for the German government told Der Spiegel.

Denmark's maritime traffic agency and Sweden's Maritime Authority on Monday reported a "dangerous" gas leak in the Baltic Sea close to the route of the inactive Nord Stream 2 pipeline, which experienced an unexplained drop in pressure.

The leak, southeast of the Danish island of Bornholm, "is dangerous for maritime traffic" and "navigation is prohibited within a five nautical mile radius of the reported position," the agency warned in a notice to ships.

Following the incident, German newspaper Tagesspiegel claimed Monday that Berlin is convinced that the loss of pressure in the three natural gas pipelines between Russia and Germany was not a coincidence and suspects a "targeted attack".

The cause of the incidents remains unknown and an investigation is underway. Swedish Foreign Minister Ann Linde said on Tuesday that the disruption was caused by detonations, which indicates that it was sabotage.

The Nord Stream 2 pipeline, which runs parallel to Nord Stream 1 and was intended to double the capacity for undersea gas imports from Russia, was blocked by Berlin in the days before the start of the war in Ukraine.

Russian energy giant Gazprom progressively reduced the volumes of gas being delivered via the Nord Stream 1 until it shut the pipeline completely at the end of August, blaming Western sanctions for the delay of necessary repairs to the pipeline. 

When asked about the possible causes of sudden pressure loss in three of the Baltic Sea gas network's lines, Kremlin Spokesperson Dmitry Peskov suggested that the Nord Stream pipelines had been damaged in an act of sabotage.

In a press conference on Tuesday, Peskov commented on a statement issued by Nord Stream AG, the network's operator, saying that three offshore lines of the Nord Stream pipeline system sustained "unprecedented" damage in just one day.