MOSCOW, Oct 27 (Reuters) - The Russian rouble dived on Tuesday as a monthly deadline for exporters to convert foreign currency earnings loomed and uncertainty over the resurgence of the COVID-19 pandemic and the Nov. 3 U.S. presidential election unsettled markets.

Opinion polls showing a solid lead for Democrat Joe Biden have reduced appetite for Russian assets, with investors anticipating greater friction between Washington and Moscow.

By 1630 GMT, the rouble was 0.8% weaker against the dollar at 76.99. Versus the euro, it lost 0.9% to trade at 91.10.

Markets are focused on rising numbers of coronavirus infections around the world and the resulting restrictions that could derail a global economic recovery.

Russia has said it will not impose strict lockdowns despite regularly recording more than 15,000 new daily infections. From Tuesday, it ordered the wider use of face masks and recommended bars and restaurants close overnight to try to contain the spread.

Brent crude oil, a global benchmark for Russia's main export, was up 2.1% at $41.29 a barrel, recovering ground after a sharp drop in the previous trading session.

Foreign currency intervention by the central bank has supported the rouble. Daily forex sales are set to rise to the equivalent of 9.8 billion roubles from Monday, Reuters calculations show.

The bank, which reports its foreign currency sales with a two-day lag, said it sold 8.6 billion roubles worth of forex last Friday.

The currency faltered as the end of a monthly tax period approached. Export-focused companies have only one more day to convert their foreign currency to meet local duties.

Russian stock indexes fell. The rouble-based MOEX Russian index hit a more than three-month low.

The MOEX was 0.8% lower at 2,763.0 points. The dollar-denominated RTS index was down 1.8% to 1,131.4 points.

For Russian equities guide see

For Russian treasury bonds see ($1 = 76.2604 roubles) (Reporting by Alexander Marrow; Editing by Barbara Lewis)