UPDATE 2-Russian rouble slips past 70 vs dollar to near 3-week low

(Updates prices, adds Alfa Capital comment)

By Alexander Marrow

Jan 30 (Reuters) - The Russian rouble slid to a near three-week low against the dollar on Monday, as support from month-end tax payments waned and daily sales of Chinese yuan did little to buttress the Russian currency.

The rouble was 1% weaker against the dollar at 70.18 by 1513 GMT, its weakest mark since Jan. 11.

It lost 1.4% against the euro to 76.53, a three-week low, and shed 1.2% versus the yuan to 10.39 .

The rouble usually gains support from month-end tax payments when exporters convert foreign exchange revenue to pay local liabilities. A scheduling adjustment means from this year taxes are due in a single payment, which this month falls on Jan. 30.

"The Russian currency may lose tax period support this week and be at risk of further declines," Veles Capital said in a note.

The rouble is supported by foreign currency sales by the government, which is offloading up to 3.2 billion roubles ($46 million) per day of Chinese yuan.

Those sales should support the rouble in the short term, compensating for the shortfall in oil and gas revenues, said First Asset Management in a note, expecting the currency to trade in the 68-71 range against the dollar in the near-term.

Other analysts played down its effect, with Alexander Dzhioev of Alfa Capital stating that the amounts being sold were too small to have a significant impact on the rouble.

"The triggers for weakening are the sharp recovery in imports and the relaxing of controls on the movement of capital," Dzhioev said.

The rouble has been under external pressure since a Western price cap on Russia's oil sales came into force in early December alongside a European Union embargo of Russian oil exports, forcing Moscow to sell at a discount.

Brent crude oil, a global benchmark for Russia's main export, was down 0.9% at $85.9 a barrel.

Russian stock indexes were mixed.

The dollar-denominated RTS index was down 0.5% at 987.9 points while the rouble-based MOEX Russian index was up 0.5% at 2,200.9 points.

Shares in state telecoms provider Rostelecom jumped 4.3% after a report by daily paper Kommersant said the company was in talks to buy rival Megafon. ($1 = 69.5955 roubles) (Reporting by Alexander Marrow; Editing by David Goodman and Arun Koyyur)