MOSCOW, August 6 (RIA Novosti) - Russian investigators in Nizhny Novgorod have opened a criminal case into the illegal sale of MiG-31 Foxhound aircraft hulls at $5 instead of $3.7 million, the Prosecutor General's Office said Thursday.

The sale came to light after an anti-corruption check was carried out to see whether regulations were followed during the sale of items from the Sokol Aircraft Construction plant located in the Russian Volga city of Nizhny Novgorod.

Prosecutors said that in October 2006 - July 2007, unidentified officials from the local department of the Agency for State Reserves unlawfully included four MiG-31 hulls (without engines and weapons) into a list of sale items.

"As a result, long-range supersonic interceptor aircraft that were not for sale were purchased by a dummy firm, Metalsnab, which was not entitled to trade in arms and military hardware," prosecutors said.

The asking price of the MiG-31 hulls was significantly undervalued by a local valuation company.

According to the valuation report one hull was valued at 153 rubles ($4.9) - this initial price was accepted during bidding and the MiGs were sold at this price. However, one hull actually costs around 116 million rubles ($3.7 million).