Russian authorities have issued warnings against using Bitcoin, saying the virtual currency could be used for money laundering or financing terrorism and that treating it as a parallel currency is illegal.

"Systems for anonymous payments and cyber currencies that have gained considerable circulation ? including the most well-known, Bitcoin ? are money substitutes and cannot be used by individuals or legal entities," the Russian Prosecutor General's Office said.

It added that Russian law stipulates the rouble is the sole official currency and that introducing any other monetary units or substitutes was illegal.

Russia's central bank has also said that Bitcoin trade was highly speculative and the unit risked losing value.

"Citizens and legal entities risk being drawn, even unintentionally, into illegal activity, including laundering of money obtained through crime, as well as financing terrorism," it warned.