The Bank of Portugal said Monday that it has sold 15 metric tons of its gold reserves "in recent months," as part of its continuing effort to diversify its reserve holdings.

The bank didn't specify the timing of the gold sales or give prices for the yellow metal.

The Bank of Portugal sold the gold under the terms of the Sept. 27, 2004, agreement among central banks. That agreement allows the signatory banks to sell up to 2,500 tons of gold.

The Portuguese central bank last reported gold sales Dec. 19, 2005, when it announced the sale of 10 tons from its reserves.