Boosted by a jump in oil prices above $80 per barrel and local month-end tax payments, the rouble gained 0.5 percent to 66.10 versus the dollar as of 0715 GMT, hovering at levels last seen on Aug. 9.

Versus the euro, the rouble firmed 0.5 percent to 77.64 .

"This week, the issue of trade wars, along with the FOMC rate decision due on Wednesday, will be of paramount importance for both EM currencies in general and the rouble in particular," VTB Capital said in a note.

Since the US Fed is widely expected to increase rates and this is already priced in by the market, the rouble has chances to appreciate more after the rate move, VTB Capital said.

Month-end taxes should also help the Russian currency recover further from more than two-year lows it hit as export-focused companies usually convert dollar revenues to meet local liabilities.

On the stock market side, shares in EN+ outperformed on the Moscow Exchange by gaining 6.1 percent after the US Treasury extended until Nov. 12 the deadline for investors to divest holdings of debt, equity and other assets in two Russian sanctioned companies, EN+ and Rusal.

Shares in Rusal, Russia's largest aluminium producer were up 0.5 percent.

The US Treasury in April imposed sanctions against billionaire Oleg Deripaska and eight companies in which he is a shareholder in response to what it termed "malign activities" by Russia. Deripaska has held a controlling interest in EN+, which in turn controls Rusal.

The dollar-denominated RTS index was up 0.8 percent to 1,158.8 points, its highest since Aug. 1, while the rouble-based MOEX was 0.2 percent higher at 2,430.2, a notch away from its all-time high of 2,434.94 hit last week.