The Russian ruble has plunged 2.3 percent to hit a seven-month low amid a further drop in oil prices, the country's key export.

The ruble traded at 70.7 to the dollar in early trading in Moscow on Monday, its lowest level since Jan. 30, when the Russian markets were hit by a combination of low energy prices and Western sanctions.

Oil is the backbone of the Russian economy and the fall of the ruble follows a sharp decline in the price of crude oil. Crude fell further on Monday, with the U.S. contract having on Friday dropped below $40 per barrel for the first time since 2009.

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