Russian naval ships were reportedly spotted on Monday and Tuesday in the vicinity of the Nord Stream pipelines where the leaks were detected.
European security officials observed the naval support ships near the Baltic pipelines though it is unclear whether the vessels had anything to do with the explosions alleged to have caused the leaks, said a report by CNN quoting unnamed intelligence sources.
The report added that Russian submarines were also seen close to the region last week.
The leaks on the Nord Stream 1 and Nord Stream 2 pipelines were discovered on Monday and Tuesday. Though neither were operating at that time, they were full of gas which began to bubble up to the surface.
According to a Danish military official, the presence of Russian ships doesn't mean Russia had anything to do with the leaks.
"We see them every week. Russian activities in the Baltic Sea have increased in recent years. They’re quite often testing our awareness – both at sea and in the air," the official told CNN.
Though the US officials have refused to comment on CNN's report, speculations are rife that Moscow had a role in the blast and subsequent leaks.
However, Kremlin spokesman Dmitry Peskov dismissed these accusations as "predictable, stupid and absurd". He added that it would be wise to wait for examination into these ruptures before making any accusations. The Russian prosecutor's office has also launched a "international terrorism" probe into the incident.
The German operator of the pipelines, Nord Stream AG, said it’s preparing a survey to assess the damage. "Currently, it is not possible to estimate a timeframe for restoring the gas transport infrastructure. The causes of the incident will be clarified as a result of the investigation,” a company statement said.
The European Union has already launched an investigation into the mystery leaks after seismologists too had reported powerful explosions just before the leaks. While the first explosion was recorded early Monday southeast of the Danish island of Bornholm, the second happened northeast of the island that night. Seismic stations in Denmark, Norway and Finland have recorded the explosions.
Meanwhile, Sweden's coast guard has reportedly found a fourth gas leak on the damaged Nord Stream pipeline. A report by Retuers quoted a Swedish newspaper Svenska Dagbladet which claimed that two of these four are in Sweden's exclusive economic zone (EEZ). The other two are in Danish EEZ.