Russia’s prime minister has sent a letter to the Swedish government requesting a role for Russian authorities in the investigation into the explosions that damaged the Nord Stream pipelines, Sweden’s foreign ministry said on Friday.

A Swedish crime scene investigation of the Nord Stream 1 and 2 gas pipelines from Russia to Europe has found evidence of detonations and prosecutors suspect sabotage.

“On October 6, a letter was received from Russian Prime Minister Mikhail Mishustin to Prime Minister Magdalena Andersson requesting that Russian authorities and the company Gazprom be involved in the Swedish investigation,” the Swedish Foreign Ministry said in an e-mail.

Sweden has previously rejected calls from the Kremlin for Russia to be part of the investigation.

Maria Zakharova, spokeswoman for the Russian foreign ministry, said on Thursday that Moscow would insist on a “comprehensive and open investigation” that includes Russian officials and Gazprom.

“Not to allow the owner (of the pipelines) to witness the investigation means there is something to hide,” Zakharova said.

Swedish and Danish authorities have been investigating four leaks after the pipelines, which link Russia and Germany via the Baltic Sea and have become a flashpoint in the Ukraine crisis, were damaged at the start of last week.

Europe, which previously relied on Russia for about 40 percent of its gas, is facing an energy crisis in the aftermath of Moscow’s invasion of Ukraine which has drastically cut supplies of the fuel.