At 0739 GMT, the rouble was 0.22 percent weaker against the dollar at 65.94 and had lost 0.35 percent to trade at 74.65 versus the euro.

On Thursday the rouble touched a two-month high at 65.68 per dollar but the central bank statement on Friday weakened its position.

The central bank said it would begin carrying out its delayed 2018 foreign currency purchases on Feb. 1, increasing daily forex purchases by 2.8 billion roubles over 36 months.

The central bank resumed purchases on Jan. 15 after having stopped them in August at a time when the rouble was especially volatile.

"Market participants probably interpret the message very simply and forthrightly as an important signal that the strengthening of the rouble would not last long," analysts at Rosbank said in a note.

Oil prices supported the rouble as they rose more after Washington signalled earlier it could impose sanctions on Venezuela's oil exports.

Brent crude oil, a global benchmark for Russia's main export, was up 0.82 percent at $61.59 a barrel.

The rouble has also received support from month-end tax payments. These usually prompt export-focused companies to convert their revenues on the market to meet local obligations, which are supportive of the rouble.

Russian stock indexes were up.

The dollar-denominated RTS index was up 0.1 percent to 1,189.15 points. The rouble-based MOEX Russian index was 0.25 percent higher at 2,488.86 points.

The situation in Venezuela is still the main geopolitical focus for the Russian market. The Russian government and oil giant Rosneft have handed Venezuela at least $17 billion in loans and credit lines since 2006.

The shares of Rosneft down 0.7 percent in early trade on Friday, but then restored positions rising by 0.2 percent.