Authorities named a gas leak as the likely cause for the blast that killed 39 people on Dec. 31 and devastated a 10-story apartment block, causing part of it to collapse. Investigators said no traces of explosives had been found in the rubble as rumors and anonymously sourced reports pointed toward terrorism, citing a minivan explosion the next day that killed three people on a nearby street.

Islamic State has reportedly claimed responsibility for a deadly explosion in Russia’s industrial city of Magnitogorsk on New Year’s Eve that killed over three dozen people, monitoring groups have said, contradicting the official explanation for the events.

The Islamic State terrorist group-affiliated Al Naba newspaper claimed credit for the fatal explosion in Magnitogorsk, three terrorist monitoring groups said early on Friday, citing an "exclusive" issue of the weekly newspaper.

The Terrorism Research and Analysis Consortium (TRAC) said an Islamic State affiliate in the North Caucasus had planted a bomb “between the third and 10th floors” of the apartment block in the Urals city.

Russia's Investigative Committee released a statement Friday saying that all explanations were being considered in its ongoing probe into the blast. The committee said that a gas leak was being considered as the most likely explanation and reiterated that no traces of explosive materials had been found at the site of the explosion.

"I call on journalists to refrain from trusting the messages of terrorist organizations, which, as is well-known, attribute all high-profile incidents in the world to themselves," the committee's spokesperson, Svetlana Petrenko, said in the statement.

Meanwhile, a widely circulated report published Friday by journalist Nikita Mogutin claimed that the apartment blast had been caused by explosives planted by three men who had planned a series of terrorist attacks in Magnitogorsk on New Year's Eve. The unconfirmed report based on unnamed sources claimed that another explosive device had been found in the city on Jan. 1 and that the three plotters had been killed after attempting to flee security forces.

Islamic State is a terrorist organization banned in Russia.