The Group of 20 key developed and developing countries, at their April summit in London, agreed the gold sales should allow the IMF to offer favorable conditions on loans to the poorest countries.
The IMF decision comes ahead of a two-day G20 summit in Pittsburgh, Pennsylvania, that opens next Thursday. Hosted by US President Barack Obama, the leaders are to discuss efforts to recover from the worst global recession in six decades and financial regulatory reform.
"The new income model is designed to provide the fund with more diverse income sources that are better aligned with the variety of functions performed by the fund, with a central component being the funding of an endowment with the profits from these limited gold sales," the 186-nation institution said.
The IMF said the sales "will also increase the fund's resources for lending to low-income countries," a strategy that won board backing in July.
"I am delighted that the executive board has given its overwhelming backing to a strictly limited sale of fund gold to put the financing of the IMF on a sound long-term footing, and enable us to step up much-needed concessional lending to the poorest countries," IMF managing director Dominique Strauss-Kahn said in the statement.
"These sales will be conducted in a responsible and transparent manner that avoids disruption of the gold market," he said.
The amount of gold to be sold is one-eighth of the 3,217 tonnes of gold currently held by the Washington-based IMF, the third-largest official holder of gold after the United States and Germany.
Board approval required an 85 percent majority of the total IMF voting power.
The United States, by far the largest stakeholder, gave its green light after Congress passed legislation authorizing the sale and President Barack Obama signed it into law on June 24.
The fund is required by its founding document to conduct all gold sales at market prices.
The IMF did not state the value of the gold to be sold but based on the current bullish near-record market price for the metal, it is estimated the sale would fetch 13 billion dollars.
Under the approved plan, the IMF would offer to sell gold directly to central banks "or other official sector holders if there were to be interest from such holders."
The IMF said such transactions would redistribute official gold holdings without changing total official holdings.
If official demand is insufficient, the IMF said it could conduct the gold sales "on-market in a phased manner over time," in line with an approach already followed by central banks.
The IMF would be constrained by the overall ceilings agreed by the central banks, which currently is 400 tonnes annually for the next five years, starting on September 27.
The IMF said it "will inform markets before any on-market sales commence" and "report regularly to the public on the progress with the gold sales."
In July, the IMF announced it would increase its lending to poor countries, mostly in Africa, to 17 billion dollars by 2014, including 8.0 billion over the next two years.
That compares with an annual average of one billion dollars in the 2006-2008 period to poor countries, and three billion dollars in the first half of 2009.
The IMF also had decided to cancel interest payments owed by poor countries through end-2011 and reform lending practices to make loans quickly available, at higher ceilings on amounts and with more flexible conditions.
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