Washington and Moscow have both denied any involvement in the blasts and each has pointed the finger at the other

An investigation into the ruptured Nord Stream 1 and 2 pipelines led the Swedish Prosecution Authority to announce Friday findings of "serious sabotage."

Swedish and Danish investigators have been studying a series of explosions on Sept. 26 that ruptured the Nord Stream 1 and 2 gas lines. The pipelines run from Russia through the Baltic Sea and into northern Germany.

The gas explosions triggered four leaks -- two in Denmark's exclusive economic zone and two in Sweden's. Last month, Danish Police said the gas leaks were caused by "powerful explosions."

Sweden's prosecutor's office on Friday said the investigators found evidence of explosives and foreign objects. A statement from the Swedish Prosecution Authority said that the discovered detonation sites are under further investigation.

Some believe that the gas pipe explosions resulted from tensions between Moscow and the European Union over an energy crisis stemming from Russia's invasion of Ukraine. In February, after the start of the invasion, Germany denied the Nord Stream 2 pipeline an operating permit.

Russia shut down Nord Stream 1 in August. While Moscow argues that the closure of Nord Stream 1 was to repair leaks, some have argued that it was a form of retaliation against NATO countries over sanctions imposed over the war in Ukraine.

Europe has faced skyrocketing energy costs this year as a result of Russia's invasion. In February, gas prices began to rise as many countries decided to cut ties with Russian oil, and the closing of Nord Stream 1 and 2 only aided stress.

In October, Germany bought natural gas from France. It was the first time Germany and France had made an energy deal, with France now supplying Germany with 2% of its daily natural gas needs.

After the gas leaks were first reported, Russian President Vladimir Putin said the gas leaks were an "act of international terrorism." On Friday, Kremlin spokesperson Dmitry Peskov said Russia would not repair the pipeline until it received a full damage report.