25-year-old chemistry student Vladimir Likhonos, from the city of Konotop in northern Ukraine, died at his parent's house - after relatives heard what was described as 'a loud pop', and rushed into his room.

There they discovered that the lower half of his face had been severely disfigured by the chewing gum blast, with his jaw entirely blown off.

Medical workers who arrived on the scene attempted to treat his injuries but were unable to save him.

Forensic tests carried out on the chewing gum revealed an unidentified chemical substance on it, the Russian news agency Ria Novosti said.

.It is thought that the student, who has not been named, had a habit of dipping his chewing gum into powdered citric acid - and investigators believe that he may have mistakenly dipped the gum into the wrong substance, as the two powders appeared very similar, leading to the deadly explosion.

'Anybody could have mixed them up,' said police spokeswoman Elvira Biganova.

Authorities are waiting on the results of further tests by explosives experts to identify the mystery substance