Failure to de-ice a Russian passenger plane before takeoff was the most likely cause of a crash in Siberia that killed 31 of the 43 people aboard the UTair ATR 72-200 craft, federal investigators said on Wednesday.

At the moment, on the basis of the materials received, the investigators consider the failure to conduct a de-icing procedure to be the most probable causes of the air crash (on Monday), Russia's Investigative Committee said on its website.

(Writing by Steve Gutterman, Editing by Timothy Heritage)