SYDNEY--The central banks of Russia, Kazakhstan and Belarus topped up their official gold reserves last month, while countries including Tajikistan and Mozambique cashed in some of their holdings as gold prices rose, data from the International Monetary Fund show.

Emerging markets again dominated gold-market activity among central banks in December, continuing a trend that emerged in recent years as expanding economies sought to diversify their assets amid turbulence in global markets.

Russia, which has one of the world's largest holdings of the metal, added around 666,500 troy ounces to its 38.8-million ounce stockpile last month, according to the IMF data Tuesday. Kazakhstan meanwhile lifted its reserves 2.2% to 6.2 million ounces, and Belarus 3.3% to 1.4 million.

The Netherlands also increased its official reserves by 309,000 ounces, or 1.6%, to 20 million ounces--the first change to its holdings since 2008, according to the IMF data. The Dutch central bank, which in November announced it would repatriate some of its gold reserves from the U.S. in an effort to spread its gold stock in "a more balanced way," wasn't immediately available for comment.

Malaysia too acquired extra gold for its reserves, which rose to 1.2 million ounces from 1.1 million.

Some central banks cut their gold holdings, though, at a time when global bullion prices started rising amid jitters over the European outlook. The gold price averaged US$1,202 an ounce in December, up from US$1,176 an ounce the month prior, according to The London Bullion Market Association.

In December, Mozambique cut its holdings of the precious metal by 15% to around 175,000 ounces, while Tajikistan lowered its reserves 11% to just below 278,000 ounces, according to the IMF data.

Turkey's central bank reported a decrease of more than 124,000 ounces to the IMF, taking its official reserves to 17.0 million ounces--although analysts say volatility in the country's reserves largely results from a central-bank decision to start accepting gold as collateral from commercial banks in late 2011.

Write to Rhiannon Hoyle at rhiannon.hoyle@wsj.com

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