The Russian rouble strengthened on Wednesday in volatile trade after the finance ministry said it had started selling foreign currency.

Reuters reports that the Russian currency has come under heavy selling pressure this week, forcing the central bank to hike its key interest rate by an unexpected 650 basis points, in an emergency move that did little to buttress the currency.

The rouble is up 0.32% against the dollar at 68.52 from close of US markets and is at 84.56 to the euro.

However, after Tuesday’s huge swings in the currency market, which saw the rouble swing between 58.27 and 80 to the dollar and then back to 70, the currency initially traded down more than 6%  on Wednesday to trade at 72.2 to the dollar as the central bank’s hiking of interest rates at 1am on Tuesday continued to have little effect.

Oil and gas account for 75% of the country’s exports and more than half of its budget revenues - Brent crude for February delivery is trading this morning at $60.10. The benchmark for about 65% of world oil trade is down 48% from its June 2014 peak.

The Economist says: "During 2015 Russia’s firms must repay $100bn-worth of foreign debt. But as the rouble falls, paying back dollars becomes more difficult. Energy giants like Gazprom and Lukoil are in much worse shape than people had realised. Rosneft, an oil company, has been leaning on the Kremlin for financing. Earlier this year it requested a $44-billion bail-out from the Kremlin; on December 12th the central bank helped it out with a $7bn rouble-denominated bond. The latter deal amounts to printing roubles to buy dollars—a sure-fire way to weaken a currency further."

It adds: "There is a real risk now that Russia's currency crisis could develop into a much bigger banking crisis. The population may start a run on the banks. A rash of corporate bankruptcies could leave the Kremlin on the hook for a big chunk of debt. No wonder confidence in the prop provided by the Kremlin’s foreign-exchange reserves, officially valued at $370bn but in practice much lower, is waning."

However, almost half of the reserves are invested in sovereign funds and are therefore not liquid.

The FT reports that Alexei Ulyukayev, Russia’s liberal economy minister, reassured markets on Tuesday saying that capital controls were “not discussed” at a meeting of the government on the economic situation.

However, index provider MSCI said on Wednesday that it could exclude Russia from the closely-followed MSCI Emerging Markets index if capital controls were introduced.

“The introduction of restrictive measures, such as capital or foreign exchange controls, which may lead to a material deterioration of Russian equity market accessibility, may lead to the exclusion of the MSCI Russia Index from the MSCI Emerging Markets Index,” it said.

Here’s a look at other notable oil producers and their fiscal breakeven points for 2014 and 2015, according to Citi Research’s data via Marketwatch

The FT's John Authers reports on a confusing Tuesday for international markets, as the Russian rouble tried to find level ground. Wednesday's meeting of the Federal Reserve's rate-setting committee now appears to have grown in importance.