European security officials reported seeing Russian Navy ships earlier this week in the vicinity for the Nord Stream pipeline leaks, CNN reported.
Russian submarines also were seen in the area last week, CNN reported Friday.
Underwater explosions likely caused leaks to the Nord Stream 1 and 2 pipelines from Russia to Germany. European Union (EU) leaders have denounced the incident as sabotage.
One Danish military official cautioned that Russian ships are seen "operating in the Baltic Sea pretty routinely," CNN reported.
The network added that Denmark and Sweden were investigating the cause of the leaks, with the U.S. saying it would provide intelligence it had gathered.
CNN said U.S. officials still did not have a "firm sense" about what happened to cause the leaks.
The leaks occurred amid Russia's war in Ukraine. President Vladimir Putin last week ordered a partial mobilization of reservists in Russia, in a measure that appeared to be an admission the war isn't going according to plan after nearly seven months of fighting.
EU leaders will discuss next week the sabotage on the pipelines, said an official, who added that the incident had changed the nature of the conflict in Ukraine fundamentally.
The Kremlin said Thursday that incidents on the undersea gas pipelines from Russia to Germany look like acts of state-sponsored "terrorism."
A Moscow spokesman called claims that Russia caused the leaks "predictably stupid."
Europeans had not been able yet to send divers to conduct a site inspection of the leaks.
Nord Stream AG, the operator of the Russia-led Nord Stream 1 offshore gas pipeline said Thursday it intended to start assessing the damage to the pipeline as soon as it receives necessary official permits.
Reuters reported Wednesday that a Western official said the leaks are a very serious development and highly suspicious, but a full investigation is needed to establish what happened.
Methane leaking from the damaged Nord Stream pipelines is likely to be the biggest burst of the potent greenhouse gas on record, by far.
The Associated Press and Reuters contributed to this story.
© 2022 Newsmax. All rights reserved.