By Andrey Ostroukh 

MOSCOW--The ruble strengthened in early trade Wednesday after the Russian Finance Ministry said the beleaguered currency is "extremely undervalued" and announced plans to start selling its excess foreign-exchange holdings.

But trading remained volatile, with the currency falling as much as 5% against the dollar shortly after the market opened and then reversing to trade more than 5% stronger. In late morning, the ruble was trading around 66.40 a dollar, down from 67.50 at the end of Tuesday. Oil prices were slightly weaker.

The Finance Ministry said it "considers the ruble to be extremely undervalued and has started selling foreign currency from its balances on the market."

The ministry later said its holdings total about $7 billion, but it didn't specify how much it would sell. "We'll be selling for as long as we need to," the Interfax news agency quoted Deputy Finance Minister Alexei Moisseyev as saying.

"Calming the population and pre-emptively addressing any banking sector issues is of the utmost importance, especially ahead of the weekend," Alfa Bank said in a note. "However, given yesterday's price action [the ruble swung 32% intraday without much central bank support], it seems that the monetary authorities at least for now are willing to let the market find its own equilibrium."

The central bank, which has vastly greater currency reserves of $416 billion, showed no sign of intervening in the market Wednesday, traders said. Its limited sales of dollars and euros in recent days--it spent $1.96 billion on Monday--haven't been enough to slow the ruble's drop.

"The big market theme is still of position liquidation," said Société Générale strategist Kit Juckes. "Money is leaving Russia rather than short ruble positions being put on."

After an emergency meeting Tuesday with Prime Minister Dmitry Medvedev, Russian officials said additional measures were planned to stabilize the financial markets. A 6.5-point interest rate rise to 17% on Monday night did little to calm the markets Tuesday, and the ruble plunged to record lows of 80 a dollar, before recovering some of the lost ground late in the day.

President Vladimir Putin has maintained public silence on the ruble's woes this week. His spokesman told a local newspaper Tuesday that he planned no "special statements' on the situation but would likely address it at his annual news conference, scheduled for Thursday.

Valentina Matvienko, speaker of the upper house of parliament, played down the crisis saying, "this has to be viewed like bad weather which will pass. We can't oversimplify the situation but we shouldn't sow panic because that will only make things worse," the Interfax news agency quoted her as saying at the opening of the session Wednesday.

Many Russians reacted with shock this week to the huge drops in the exchange rate, gyrations reminiscent of financial crises in 2008 and 1998 that battered the economy and confidence. Banks reported surging demand for foreign currency, with lines at branches and ATMs and some running out of dollars and euros. Interfax reported that a number of major banks in the industrial city of Chelyabinsk had run out of foreign-currency cash.

Retailers also were scrambling to keep up. Major Auto, a large chain of car dealers, said it suspended sales of autos Tuesday amid the ruble moves, though many models, especially luxury brands, had already sold out. Consumers had been racing to spend their depreciating rubles on durable goods such as vehicles, appliances and electronics in recent weeks before stores raised the ruble prices.

Write to Andrey Ostroukh at andrey.ostroukh@wsj.com

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