The Russian airliner that was destroyed midair Saturday killing all 224 people on board was caused by outside factors, according to the owner of the company, feeding into claims by Islamic State group that they downed the aircraft. Moscow in response, has said there is no proof of this and asked that speculation be avoided until investigators release at least preliminary results.

The circumstances surrounding the plane’s destruction are still unclear, however according to the Russian Metrojet airline executive, Alexander Smirnov, who held a news conference in Moscow, the only reasonable explanation is “an external influence” saying that planes do not just break apart midair, reported CNN.

“We exclude technical problems and reject human error,” said Smirnov. “There is no combination of system failures that could have broken the plane apart in the air.”

The airline guaranteed the Airbus A321-200 plane had passed all the required tests, including one for metal fatigue in 2014, an inspection that must be carried out every six years.

One of the main indicators that it was not an internal problem is that there was no distress call and the crew did not issue any communications during the final moments. According to experts, this indicates that the flight crew must have been disabled and not able to communicate with air traffic controllers.

Kremlin spokesperson Dmitry Peskov has urged an end to speculation until the investigation sheds some insight as to the motives of the accident that occurred just 26 minutes after take off, causing the aircraft to come crashing down from an altitude of about 31,000 feet.

“It would be wrong to articulate any preliminary guesses or voice statements that are not based on anything,” said Dmitry Peskov, the spokesman for the Russian president, on Monday. “Let the investigators produce at least some results first.”

Other experts speculate that a bomb may have been planted on the plane, however Smirnov also seemed to reject this suggestion saying the crash was definitely caused by outside factors.

President Vladimir Putin spoke for the first time Monday about the tragedy, calling for an “objective” investigation and expressed condolences to the families of the victims.

According to news reports, the extremists Islamic State group claimed responsibility for the destruction saying it shot down the aircraft that was flying over the Sinai desert, however Russian officials have dismissed this claim saying the airliner was flying to high to be hit by a ground missile.

Russian officials initially claimed Sunday that a Russian airliner that crashed in Egypt broke apart midair under unclear circumstances.

“The plane broke up in midair and its fragments are scattered over a vast area of about 20 square kilometers,” said Viktor Sorochenko, head of Russia's Interstate Aviation Committee.

According to Russian state media, Sorochenko made the comments after visiting the crash site of flight KGL9268. The airliner crashed in Egypt's Sinai Peninsula Saturday morning, killing all 224 passengers and staff.

Sorochenko said the cause of the crash remained unclear, stating an investigation is ongoing.

“It is too early to speak about the crash causes,” he said, according to Russia's Tass news agency.

Around 100 Russian emergency workers have been deployed to the crash site to collect debris, and President Vladimir Putin has declared a national day of mourning.

Egypt's President Abdul Fattah al-Sisi has stated a full investigation into the crash could take months. Authorities in Egypt have already concluded claims that Sinai militants downed the aircraft are unlikely. According to Egyptian Prime Minister Sharif Ismail, Sinai militants are not believed to possess weapons capable of hitting a commercial airliner at over 9,000 meters.

Shortly after the crash Saturday, militants claiming to be affiliated with the Islamic State group said they were responsible for the disaster.

“The soldiers of the caliphate succeeded in bringing down a Russian plane in Sinai,” the militants said in a statement circulated online. Both Russian and Egyptian authorities have said the statement lacks credibility, though a number of international airlines have said they won't fly over the Sinai until further information is made available.