No one has taken responsibility for the explosions, which damaged Nord Stream gas pipelines.
Germany is set to form a joint investigation unit with Denmark and Sweden to probe the apparent "sabotage" against the underwater Nord Stream gas pipelines from Russia.
Interior Minister Nancy Faeser told the weekly Bild am Sonntag on Saturday that she had agreed with her fellow interior ministers that the work would be conducted by a "joint investigation team under EU law" with staff from the three countries.
"All indications point to an act of sabotage against the North Stream pipelines," she was quoted as saying. She added the team would bring in expertise from "the navy, police and intelligence services".
Authorities are practising "increased vigilance" to protect Germany's energy infrastructure but said there were "no concrete threat indications for German sites – as of now".
Caused by saboteurs
Faeser had told the daily Sueddeutsche Zeitung on Friday that German police were patrolling the North and Baltic Seas with "all available forces" following the explosions, in cooperation with neighbouring countries.
The Nord Stream pipelines, where flows have been halted since the end of August, were key arteries for the delivery of natural gas directly from Russia to Germany.
The source of the explosions has remained a mystery, however, with both Moscow and Washington denying responsibility.
Russia and the European Union have suggested the ruptures were caused by saboteurs.
British Prime Minister Liz Truss met her Danish counterpart Mette Frederiksen on Saturday and discussed what they agreed was "sabotage" to the Nord Stream gas pipelines, Truss's office said in a statement.
European leaders have promised to respond to what they call sabotage, following three gas leaks in the Nord Stream pipelines.— TRT World (@trtworld) September 29, 2022
While it's still unclear who, if anyone, might be behind it, some officials are blaming Moscow pic.twitter.com/vjJNcRT19N