Swedish officials confirmed on Friday that the September blasts that destroyed parts of the Nord Stream pipelines that carry natural gas from Russia to Germany under the Baltic Sea were acts of sabotage.

“The analyzes carried out have found traces of explosives on several foreign objects” found at the sites of the explosions, prosecutor Mats Ljungqvist, who is leading the investigation, said in a statement.

Ljungqvist added that technical analysis would continue in order to “draw more reliable conclusions regarding the incident”.

The Swedish prosecutor’s office said that “the continued investigation will show whether anyone can officially be suspected of a crime”.

Four large gas leaks were discovered in Nord Stream’s two pipelines off the Danish island of Bornholm in late September, with two underwater explosions recorded shortly beforehand by seismic institutes.

Investigators had already said that preliminary investigations had substantiated the suspicion of sabotage.

While the leaks were in international waters, two of them were in the Danish exclusive economic zone and two of them were in Sweden.

In late October, Nord Stream dispatched a Russian-flagged civilian vessel to inspect damage in the Swedish zone.

The pipelines linking Russia to Germany were at the center of geopolitical tensions as Russia cut off gas supplies to Europe in alleged retaliation for Western sanctions over Moscow’s invasion of Ukraine.

Although the pipelines were not operating when the leaks occurred, both still contained gas that was leaking through the water into the atmosphere.

Both Washington and Moscow have denied any involvement, pointing fingers at each other.