Russia’s ruble went into free fall on Tuesday, plunging 20 percent and more to record lows in spite of a surprise overnight move by the country’s central bank to sharply boost interest rates.

The drop in the ruble’s value – it sold as low as 80 to the U.S. dollar at one point in trading on Tuesday – has been caused primarily by the steep decline in global oil prices, although Western sanctions aimed at punishing the Kremlin for its illegal annexation of Ukraine’s Crimea territory and its backing of separatist rebels in eastern Ukraine have also taken their toll.

Russia’s economy, which analysts say is headed for recession next year, is heavily dependent on oil and natural gas sales to finance what remains a heavily government-directed economy.

The ruble is down more than 60 percent this year as investors have pulled more than $100 billion out of the troubled Russian markets.

Officials of Russia’s central bank met in an emergency session at midnight Monday local time, invoking an interest rate hike from 10.5 percent to 17 percent – the biggest boost in the cost of borrowing in Russia since the country’s 1998 default.

The move, aimed at slowing demand for dollars and other convertible currencies and at curbing inflation, had little immediate effect beyond panicking a population that has seen its buying power shrink dramatically this year.

Prime Minister Dmitry Medvedev summoned key financial and economic officials to his suburban Moscow residence for a meeting to craft a further response to the currency crisis, Russian media reported.

“The situation is critical,” Sergei Shvetsov, central bank deputy chairman, told reporters as the ministers converged on Medvedev’s home in Gorki. He said the government hadn’t envisioned such a disaster “in our worst nightmares.”

Economic Development Minister Alexei Ulyukayev said the interest rate hike was aimed at improving hard-currency liquidity on the domestic market and that the exchange rates should stabilize under the borrowing curbs.

“We are not the first and we’re not the last to pass through similar circumstances,” the Tass news agency quoted Ulyukayev as saying.

Central bank chief Elvira Nabiullina also urged patience in turning around the collapsing ruble. She said the interest rate hike was aimed at taming inflation and would take time to gain traction.

The Sputnik news agency quoted financial analysts as saying that as bad as the current financial situation has become, the Russian economy is in much better shape to withstand the pressures than it was in 1998.

“Russia then had low reserves, a low oil price, a budget deficit and struggled to collect tax revenues,” the news agency quoted Renaissance Capital’s global chief economist, Charles Robertson, as saying.

Tuesday’s ruble plunge may have been accelerated by reports that the central bank intervened clandestinely in currency trading on Monday to help Rosneft, a major oil exporter run by Kremlin insider Igor Sechin, to raise 625 million rubles, nearly $11 billion, in bonds at a favorable exchange rate.