At 1300 GMT, the rouble was 0.1 percent stronger against the dollar at 65.96, but down 0.2 percent at 75.37 versus the euro.

After monthly tax payments that supported the rouble earlier this month, the currency has been following emerging market peers, which are waiting for the US rate decision.

The Russian Finance Ministry was also in focus as it managed to sell all 25 billion roubles ($379 million) in OFZ treasury bonds on offer, with bids totalling 86.6 billion roubles.

These weekly auctions gauge investors' sentiment towards Russia and concerns about the possibility of fresh US sanctions on holdings of Russian state debt.

US President Donald Trump's administration on Sunday lifted sanctions on aluminium giant Rusal and other companies linked to oligarch Oleg Deripaska, defying a Democrat-led push in Congress to maintain them.

After outperforming the market on Monday, shares in Rusal dropped and were down 3.8 percent on Wednesday.

The benchmark MOEX index hit an all-time high of 2,510.51 points, while the dollar-denominated RTS index briefly traded above 1,200 points for the first time since October.

Russian stocks have been boosted by oil prices rising about 1 percent on Wednesday on concerns about supply disruptions after US sanctions against Venezuela, and by the lifting of sanctions on Rusal.

But analysts say the rise in Russian stocks looks unlikely to last.

Vasily Oleinik, an analyst at Finam Brokerage, said the market's technical picture was positive overall, but that its growth potential was dwindling as the risks of a downside adjustment on the global market in February and March was high.