"Transactions will be carried out in the currency section of the Moscow Exchange in Chinese yuan -- ruble instrument with a settlement period of "tomorrow" (CNYRUB_TOM)," the finance ministry said.

It said it will allocate 54.5 billion ($798 million) roubles to sell foreign currencies between Jan. 13 and Feb. 6.

($1 = 68.6875 roubles)

(Reporting by Reuters; editing by Guy Faulconbridge)