German investigators have no evidence at this stage that Russia was behind the explosions on the Nord Stream 1 and 2 gas pipelines.
"This cannot be proven at the moment; The investigations are ongoing," Federal Prosecutor General Peter Frank told Sunday's edition of Die Welt newspaper in comments seen in advance by dpa.
With the help of two research vessels, water and soil samples as well as remnants of the pipelines had been taken, and the crime scene had also been comprehensively documented, he said. "We are currently evaluating all of this forensically."
At the end of September, a total of four leaks from the two pipelines had been discovered after explosions near the Danish Baltic Sea island of Bornholm.
The Swedish safety authorities had stated in November that it had been a case of serious sabotage - without, however, naming a culprit.
The explosion sites are in international waters in the Exclusive Economic Zones of Denmark and Sweden. Both countries are conducting their own investigations. "But we are in contact," Frank said.
Only a short time later, essential cables for the railway's radio communication system were damaged in Berlin and the western state of North Rhine Westphalia at the time. Rail traffic in large parts of northern Germany was at a standstill for hours.
The Federal Public Prosecutor's Office is also investigating these incidents that occurred on October 8. Frank said in the interview that the investigation was not yet complete. "What I can say, however: The suspicion that this was a foreign sabotage action could not be substantiated so far."
