The Russian government has cautioned against promoting “hypotheses” about the cause of the crash of a Russia-bound passenger plane that killed 38 people in Kazakhstan on Wednesday.

Some aviation experts suggested that the Azerbaijan Airlines plane had been hit by air defence systems over the Russian republic of Chechnya and pro-government media in Azerbaijan quote officials as saying a Russian missile was responsible.

Before it went down near the Kazakh city of Aktau, the plane was diverted across the Caspian Sea, from its destination in Chechnya to western Kazakhstan.

Twenty nine of the 67 people on board survived. Azerbaijan held a national day of mourning on Thursday for the victims of the crash.

“This is a great tragedy that has become a tremendous sorrow for the Azerbaijani people,” President Ilham Aliyev said on Thursday.

In Moscow, Kremlin spokesman Dmitry Peskov said: “It would be wrong to put forward any hypotheses before the investigation’s conclusions. We, of course, will not do this, and no-one should do this. We need to wait until the investigation is completed.”

The chief prosecutor in Kazakhstan said later that the investigation had not yet come to any conclusions.

But some commentators in Azerbaijani media say that Azerbaijan expects Russia to admit shooting down the plane.

Several TV channels, which are under strict control of the Azerbaijani government, on Thursday started broadcasting interviews with experts who have openly spoken about the possibility that Russia was responsible.

AnewZ channel said a preliminary investigation had concluded that the plane had been hit by shrapnel from a surface-to-air missile from Russia’s Pantsir-S defence system.

Another pro-government website, Caliber, quoted government sources as saying that no-one was claiming the plane had come under attack intentionally, but that Baku expected an apology from Russia.

When asked about the reports, the chief prosecutor’s office in Baku told the BBC that every version was being investigated.

As they try to avoid annoying Russian President Vladimir Putin, it will be very difficult for the Azerbaijani government to blame Russia directly unless it admits to shooting down the plane.

It seems that the investigation committee comprised of Azerbaijani and Kazakh officials possibly already have evidence for this, but they are waiting for Russia to announce it first.

Moscow will then have to answer questions such as why Russia did not close its airspace if there was military activity, and why it did not let the plane land as soon as possible – instead of directing it towards Aktau for landing.