The Guardian has reported referring to the classified US cables released by WikiLeaks that US diplomats have information that the gas supplies from Russia to Ukraine and the EU states are partially linked to the Russian mafia.

The newspaper said "Allegations have long swirled that the Russian crime don Semyon Mogilevich had covert interests in Swiss registered RosUkrEnergo which distributes gas from central Asia."

(Sourced from The Guardian)