The ruble weakened on Wednesday to the lowest against the dollar in seven weeks after oil, the country’s chief export, fell for a sixth day.

The currency declined as much as 1.3 percent to 31.85 per dollar, the most in a month, after oil slipped below $62 per barrel to the lowest since May 26. The 30-stock MICEX Index dropped to a two-month low.

Crude headed for its longest losing streak since December, sinking 13 percent in six days, on concern a prolonged global recession will sap demand for fuel. Russia, the world’s largest energy supplier, slumped into a deeper recession last quarter as businesses depleted inventories and lower wages crimped consumer demand, VTB Capital said Monday.

“The ruble’s strong move downward has been in the waiting for some time now,” said Ivan Tchakarov, a London-based economist for Nomura Holdings. “Obviously, oil is a strong catalyst, but the real economy is still in a very bad shape.”

Speculation that the worst of the economic crisis is passed helped fuel a rally in commodities that more than doubled the price of oil from this year’s low in January through the end of June, spurring gains in the ruble.

Oil fell as much as $1.06, or 1.7 percent, to $61.87 per barrel in New York before a report that probably will show inventories increased in the United States.