Russia's struggling ruble currency has ended a modest five-day recovery, declining 4 percent to 54 rubles against the dollar.
The ruble plummeted to lows of 80 rubles to the dollar earlier this month, battered by the combined effect of low oil prices and Western sanctions over Ukraine.
The currency rebounded this week, but saw its growth stalled after an announcement by Russia's central bank that it had lost nearly $16 billion in foreign exchange reserves between December 12 and December 19.
Meanwhile, Russia has announced that, in February, it will begin adding a duty of at least $43 per ton of wheat sent for export.
The move is meant to deter Russian wheat growers from exporting their harvests in exchange for foreign currency, a practice that has led to wheat shortages and higher prices at home.