The Public Prosecutor's Office said the remains of explosives had been found at the site, located under the Baltic Sea along the pipeline that connects Russia and Germany.
"Analysis that has now been carried out shows traces of explosives on several of the foreign objects that were found," said Mats Ljungqvist who led the investigation.
Ljungqvist said in an official statement that the findings so far in the "very complex and extensive" investigation pointed to "serious sabotage."
"The advanced analysis work continues, to be able to draw safer conclusions about the event," he added.
The Public Prosecutor's Office did not provide any further information on the probe. However it did mention that further investigation could yield evidence to name a suspect.
Russia had previously been accused of being behind the explosions that damaged the gas pipelines on Sept. 26, causing large-scale ruptures in both the Nord Stream 1 and 2, with gas visibly leaking to the surface. The Russian Defense Ministry, however, accused the West and blamed British navy personnel of blowing up the pipeline.
Two leaks had been detected in Denmark's exclusive economic zones and two in Sweden's. German authorities had halted the operation of both pipelines over the Russia-Ukraine war, though they remained filled with natural gas.
Source: Anadolu Agency