Although central banks hold one-sixth of all the gold ever mined in their reserves, their activities in the bullion market are opaque, with not a single institution revealing its day-to-day operations. In addition to holding gold for their reserves, some central banks also trade the metal, lending it on the open market in order to obtain a yield.

Thomson Reuters GFMS, the precious metal consultancy that publishes benchmark statistics on the gold market, on Tuesday said that the quantity of gold lent by central banks had risen last year for the first time since 2000.

The estimate by GFMS confirms a trend that bankers and gold traders have been privately discussing for the past six months. The increase in lending came as eurozone commercial banks, suffering a shortage of dollar liquidity, rushed to borrow gold from central banks and later swap it on the market in exchange for dollars.

“There is growing evidence that short-term loans from some central banks to commercial banks could well have increased considerably [in 2011], with the latter then using gold to swap for US dollars,” GFMS said.

As the squeeze in the dollar funding markets intensified, short-term interest rates for lending gold fell to record lows in late 2011. The rate for lending gold for one month fell to -0.57 percent in early December, implying that a bank would have to pay to swap it for dollars.

The rush among eurozone commercial banks to lend gold was one of the clearest signs of the “dash for cash” late last year that weighed on the bullion price.

Goldman Sachs said in a report that “the downward pressure from European bank funding issues has left gold prices at a steep discount to the levels suggested by US [real interest rates]”. The metal tumbled 20 percent from a peak above $1,900 a troy ounce in September to a low of $1,522 in December. On Tuesday, gold was trading at a five-week peak of $1,663.

The increase in gold lending by central banks has brought an end to a decade-long decline in the amount of bullion out on loan, as falls in hedging by gold miners reduced demand to borrow the metal.

GFMS did not put a number on the increase last year, saying only that lending had risen “by a small amount”. It estimates that the outstanding volume of swapped or leased gold stood at 700 tonnes at the end of 2010, down from a peak of about 5,000 tonnes in 2000.

Philip Klapwijk, head of metals analytics at the consultancy, was sceptical that the lending activity had affected the gold price. “This is a purely financial swap of gold for US dollars; it shouldn’t have an impact on price,” he said.

Nonetheless, GFMS maintained a cautious outlook for gold prices in the near term, predicting that the metal would average $1,640 in the first half of 2012.

“A huge amount of gold needs to be taken out of the market day in, day out by investors,” Mr Klapwijk said. “I’d be astounded if we see a reversal of sentiment but it may be that investment simply underperforms our expectations and prices sag.”

All the same, GFMS predicted that gold prices would once again gather steam later this year, touching a peak “just over the $2,000 mark” in late 2012 or early 2013.