The ruble lost 1.4 percent on the MICEX main foreign currency exchange by 2 p.m. Moscow time (1000 GMT) to reach 34.3 against the euro-dollar basket. It sank to 29 against the dollar
- a level that hasn't been seen since 2005 - and 40.8 against the euro - an all-time low.
The Central Bank set the official exchange rates for the dollar and euro in line with trading quotes.
The depreciation was the third in just five days, and the 11th since Nov. 11, when the supervised slide began.
Amid diving oil prices and the associated market downturns, it is unclear where the slide will end as the government continues its policy of a managed float rather than releasing the ruble altogether.
The Kremlin gave a sign of things to come, however, when its top economic adviser, Arkady Dvorkovich, said in comments televised Thursday that the ruble would continue to drop into the new year, and forecast a 2009 average of "a little under" 32 rubles. He said, however, that there would be no currency collapse.
The ruble is almost 14 percent down this year, and 8.8 percent down since the war in Georgia in August.
Russia's President Dmitry Medvedev said in televised remarks earlier this week that the ruble will become "a bit more flexible" to reflect the economic situation.
The Kremlin is anxious to avoid a repeat of the 1998 financial crisis, when Russians rushed to withdraw their savings as the ruble plummeted.
It has stuck to the line that it will not allow any dramatic falls in the ruble despite analysts' recommendations to devaluate the ruble in one go.