The Russian airline Kogalymavia/Metrojet has blamed “external activity” on Saturday’s plane crash which left 224 people dead.
A second Russian military jet has violated Turkish airspace in a mission that Nato says “does not look like an accident”.
Turkish F-16 fighter jets were scrambled to intercept a Russian war plane that strayed into Turkish airspace on Saturday, the Turkish foreign ministry have said.
Russian air strikes have targeted rebel-held areas in northwest Syria for a second day.
The US and Russian military will begin discussions “as soon as possible” to avoid direct clashes in the air above Syria, top diplomats have said.