Moscow, Dec 28 (RIA Novosti) Three thieves stole 250 boxes of chewing gum estimated to cost 1.7 million roubles ($57,500) from a truck in southern Russia, police said Monday.

The incident took place in southern Russia's Stavropol Territory.

'Three unidentified assailants entered a parking lot, threatened the watchman with bodily harm, and tied him up. Then they stole 250 boxes of chewing gum estimated at 1.7 million roubles from the Mercedes truck and disappeared,' the police spokesman said.

In the beginning of December, a chemistry student from the northern Ukrainian city of Konotop was killed when a stick of chewing gum exploded in his mouth.

A forensic examination established that the chewing gum was covered with an unidentified chemical substance, thought to be some type of explosive material.

Police investigation revealed that the student had a bizarre habit of chewing gum after dunking it into citric acid. On his table, police found both citric acid packets and a similar-looking unidentified substance, believed to be some kind of explosive material.

Investigators believe that the student simply confused the packets, and put the gum, covered with explosive material, into his mouth.