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."