According to Mats Ljungqvist, the Swedish prosecutor involved in the country's criminal investigation of the leaks in the Swedish economic zone, the country will not join a Eurojust Joint Investigation Team, which would require them to share their findings with Germany and Denmark.

Sweden notably reported the detection of underwater explosions on Sept. 26, shortly after which large patches of roiling gas could be seen on the surface in the same area. Nearly two weeks later, Sweden's domestic security agency said their initial investigation into the explosions had "strengthened the suspicions of serious sabotage."

Eurojust - an EU agency which coordinates judicial co-operation in criminal matters among member state agencies - said the Joint Investigation Team is "one of the most advanced tools used in international cooperation in criminal matters, comprising a legal agreement between competent authorities of two or more States for the purpose of carrying out criminal investigations."

On Friday, Germany's interior ministry said that the German Federal Police had completed their part of the investigation and turned in their findings.

Sweden's concerns over joining the team - which typically take 12-24 months to investigate - is "directly linked to national security," according to Ljungqvist in a statement to Reuters.