Investigators are considering technical failure and pilot error as the two most likely causes of Tuesday''s crash of an Antonov An-12 transport plane in Russia''s Far East, a Russian Investigation Committee spokeswoman said. The aircraft carrying 11 people and 16 metric tons of food disappeared from radars some 300 kilometers from its take-off point in the city of Magadan early on Tuesday, shortly after reporting a fuel leak and fire in an engine, Russia''s News Agency (RIA Novosti) reported. A search for the remains of the aircraft is under way, involving two Mil Mi-8 transport helicopters, a Beriev Be-200 aircraft and Antonov An-26 transport plane, as well as more than 120 emergency workers. Rain and heavy fog have hampered the search operation. The Russian Federal Air Transport Agency denied on Tuesday earlier reports that the remains of the aircraft have been discovered. A criminal case has been opened over violations of transport operation rules, which stipulates a punishment of up to seven years in prison. The aircraft, which was en route to Chukotka, belonged to the Komsomolsk-on-Amur aircraft building plant but was leased to Khabarovsk-based Avis-Amur air carrier.