This content was produced in Russia where the law restricts coverage of Russian military operations in Ukraine MOSCOW, Dec 22 (Reuters) – The trouble slumped to its weakest since late April past 72 against the dollar on Thursday as fears over the impact of sanctions on Russian oil and gas took the currency’s losses this month to more than 15%.By 0740 GMT, the ruble was down 1.8% against the dollar at 72.25, earlier hitting 72.3075, its weakest mark since April 29.It also lost 1.6% to trade at 76.82 versus the euro , also a near eight-month low, and shed 2% against the yuan to a near seven-month low of 10.28 .The trouble is continuing its “unrestrained fall”, said Veles Capital analysts. Should the ruble consolidate above the psychologically important levels of 70 per dollar, 75 to the euro and 10 per yuan, it could open up new downside horizons for the Russian currency, they said. Falling export revenues in recent months have been exacerbated by a European Union oil embargo that began in December, when an oil price cap come into force as well. Brent crude oil, a global benchmark for Russia’s main export, was up 0.3% at $82.4 a barrel. Analysts expect the ruble to gain some kind of foothold next week when month-end taxes, which usually see Russian exporters convert FX revenues to pay local liabilities, are due. Russia has been borrowing heavily in the final quarter of the year, on selling Wednesday 337.8 billion rubles ($4.7 billion) of OFZ treasury bonds. Russian banks have been buying the vast majority of government debt, with sanctions preventing access for foreign investors, who had traditionally been attracted by Russia’s high yields. MM) plans to build up its liquidity buffer using bonds with floating-rate coupons, Anatoly Popov, deputy chairman of Sberbank’s executive board, told the RIA news agency. The bank holds more than 3 trillion rubles in OFZ bonds. Russian stock indexes were mixed. The dollar-denominated RTS index (.IRTS) was down 1.8% at 923.7 points, its lowest mark since Oct. 10. The ruble-based MOEX Russian index (.IMOEX) was 0.1% higher at 2,118.1 points.For Russian equities guide seeFor Russian treasury bonds see($1 = 72.0000 rubles)Reporting by Alexander Marrow; Editing by Tom Hogue and Toby ChopraOur Standards: The Thomson Reuters Trust Principles.