Jan 11 (Reuters) - The Russian rouble strengthened on Wednesday after the central bank said it would start selling foreign currency on forex markets as early as Friday.

The finance ministry said it had set aside almost $800 million worth of foreign currency to sell for roubles from Jan. 13 to Feb. 6, starting with the sale of Chinese yuan.

The rouble was up around 1.8% against the dollar by 1126 GMT, earlier hitting a two-week high of 68.27.

It gained almost 2% against the yuan to trade at 10.08, and strengthened 1.6% against the euro to 73.74.

Brent crude oil, a global benchmark for Russia's main export, rose 0.6% to $80.55 a barrel, also supporting the currency.

Having spent long periods of last year as the world's best-performing currency, the Russian rouble lost 17% in December after Western moves to introduce an oil price cap and an EU embargo hurt the country's crude exports.

The rouble has since wound back some losses against the dollar, helped by large exporters selling off foreign currency earnings made during the first days of January to pay taxes.

Russian stock markets were higher on the day.

The dollar-denominated RTS index climbed 2.56% to 999.47, while the rouble-based MOEX Russian index was up 0.71% at 2,174.79.

For Russian equities guide see

For Russian treasury bonds see (Reporting by Caleb Davis; Editing by Andrew Heavens)