This story was last updated at 2:24 p.m.

MOSCOW (AP) — The Russian ruble plunged 2.9 percent on Monday to hit a seven-month low amid a further drop in oil prices, the country's key export.

The ruble was trading at 71.04 to the dollar at the close of trading in Moscow, its lowest level since Jan. 30, when Russian markets were hit by a combination of low energy prices and Western sanctions. After the market closed, the ruble recovered slightly in futures trading in an indication that it may recover some of its losses.

Oil is the backbone of the Russian economy and the fall of the ruble follows a sharp decline in the price of crude. The U.S. oil contract on Friday dropped below $40 per barrel for the first time since 2009 and on Monday was down another $1.23 a barrel at $39.22.

The ruble's slide was accompanied by falls in the currencies of many other post-Soviet countries, with the Belarusian ruble falling more than 5 percent to a new record low against the dollar, with a drop also recorded for the Ukrainian hryvnya and various currencies in the South Caucasus and Central Asia.

Kazakhstan's tenge was a notable exception after it recovered much of the losses from its free-float against the dollar last week, although shares in the Central Asian oil exporting nation slumped.

Russian officials have insisted that the economy is strong enough to weather the decline.

Speaking to reporters on Monday, Economic Development Minister Alexei Ulyukayev said he didn't expect the price of oil to stay below $40 a barrel in the long term. The Russian government has budgeted all of its spending on an estimated oil price of $50 a barrel.

Russian stocks were also falling, with the MICEX benchmark index down about 2 percent on Monday.

Prime Minister Dmitry Medvedev in an interview last week said he hopes Russian exporters will be encouraged to sell foreign currency, helping to stabilize the ruble.