The World Bank does not rule out the weakening of the ruble driven by an external shock, Zhelko Bogetich, the World Bank\'s chief economist for Russia, told journalists late on Thursday. The ruble has been easing against the dollar and the euro since the end of August amid the euro zone debt crisis, and Bogetich said the central bank continued adjusting its currency policy in line with a changing balance of payments and main macroeconomic indicators. In August, the central bank switched from the policy of withdrawing excess dollar liquidity maintained between February and July to selling dollars to fend off speculative attacks on the ruble. Finance Minister Alexei Kudrin has said the ruble would be weakening gradually in 2011 following a decreasing current account surplus. Deputy Economic Development Minister Andrei Klepach said on Thursday that the ruble was overvalued by 10 percent, adding he expected a sharp devaluation.