Russian officials today were trying to nail down the cause of a plane crash in Siberia which killed 31, amid reports that the craft may have become uncontrollable after icing over. 

The turboprop ATR-72 went down moments after taking off from the Tyumen airport yesterday and disintegrated on impact two kilometres away from the runway. 

Twelve people out of 43 survived and were being treated in Tyumen and Moscow. Russia's Interstate Aviation Committee, which is now deciphering the plane's in-flight recorders, said today that "the craft's engines have been working up to the moment of impact" on the snow-covered field. 

However "after the plane gained an altitude of 210 metres, it began to list, first by 35 degrees to the right, and then to the left by over 50 degrees", at which point it crashed, the committee said.