The dollar's ascent against the euro may be stifling Russian efforts to challenge the greenback's dominance as a reserve currency, with policy makers in Moscow allowing the dollar's share of foreign reserves to swell. Russia's central bank 'changed the currency structure of reserves,' raising the U.S. currency's share by 3 percentage points to 44.5 percent, BNP Paribas said Tuesday, citing Bank Rossii numbers on the final months of last year. The euro's portion fell 3.7 points to 43.8 percent. The figures, part of the central bank's annual report to parliament, aren't official yet, said a Bank Rossii spokesman who declined to be identified, citing bank policy. It's 'very much a case of economic rationalism trumping bellicose politics,' said Neil Shearing, a London-based emerging markets economist at Capital Economics, in an e- mailed response to questions. 'With the euro likely to fall further over the coming quarters and a general retreat to safe havens likely to boost the dollar, expect more of the same.' The euro has dropped 18 percent against the dollar since Nov. 25 on investor concern that policy makers may fail to contain Europe's debt crisis. Central banks have probably lost $300 billion this year on the euro and may consider cutting holdings of the currency, Stephen Jen, a managing director at hedge fund BlueGold Capital Management , said earlier this month. The dollar's share in Russian reserves will probably account for '50 percent, maybe more' of the total by the end of this year, said Julia Tsepliaeva, head of research at BNP Paribas in Moscow, in a phone interview. 'We must be prepared for changes to the allocation of various currencies on the market because the global situation isn't very stable,' Economy Minister Elvira Nabiullina told reporters in Moscow Thursday. The central bank has a 'sensible currency diversification,' she said. 'I don't think substantial changes need to be made here.' Russian policy makers have been devising alternatives since the credit crisis erupted that would allow the world's biggest energy supplier to reduce its reliance on the dollar. Officials in Moscow have been backed by Brazil, India and China seeking to limit the dollar's dominance in the $8.36 trillion of global reserves. Russian President Dmitry Medvedev has pushed for the creation of regional reserve currencies and in July produced a prototype coin for a 'world currency,' which he said was needed to stabilize the global economy. 'Common sense tells you that Russia's rhetoric doesn't always correspond to reality,' said Nikolai Kashcheev, head of research at the treasury department of Moscow-based OAO Sberbank, Russia's biggest lender. 'What we are seeing now is the central bank trying to balance reserves after skewing them toward euros.' A euro decline to $1.2150 would wipe out gains from reserve managers' efforts to diversify away from the dollar into the European currency, Jen wrote earlier this month. China may have lost $80 billion and Russia $14 billion, according to that note. The euro traded as low as $1.2144 Wednesday. Arkady Dvorkovich, an adviser to Medvedev, said last week that it would be 'absolutely incorrect' to assume the central bank had suffered losses on the scale suggested by Jen and said returns must be calculated over a longer timeframe. Dvorkovich told reporters in Moscow today the euro area economy may stagnate for months or even years. Growth will be 'very slow or even zero,' he said. 'It will be a very difficult time.' With assistance from Anastasia Ustinova in St. Petersburg, Maria Levitov in Moscow. 