(Bloomberg News) Gold climbed to the highest level in a week in thin holiday trading on reports that Iran produced its first nuclear fuel rod, spurring investors to buy the precious metal as a haven.

The bullion for immediate delivery gained as much as 3.2 percent to $1,613.40 an ounce, the highest level since Dec. 26, and was at $1,567.07 at 5:47 p.m. in Mumbai. Silver for cash delivery was little changed at $27.8625 an ounce.

A domestically made rod was inserted into the core of Tehran's atomic research reactor after performance tests, the Iranian Students News Agency reported today, citing the country's atomic energy agency. The Tehran reactor produces radioisotopes for cancer treatment, according to Mehr news agency. Nuclear fuel rods contain pellets of enriched uranium that provide fuel for nuclear power plants.

"Iran's nuclear plans have raised fears that it is getting desperate and will take some drastic step," Gnanasekar Thiagarajan, a director at Commtrendz Risk Management Services Pvt., said by phone from Mumbai. "More sanctions are expected from the U.S. and other nations. This will have a positive impact on gold prices as ideally people would try to buy gold."

The U.S. and allies are increasing pressure on Iran to halt what they say may be a covert nuclear weapons program. Sanctions signed into law by President Barack Obama on Dec. 31 aim to deter dealings with the Iranian central bank, and the European Union is considering a ban on imports of oil from Iran, the world's third-largest oil exporter. Iran denies seeking to develop atomic weapons.

Reserves Climb

Gold reserves increased in November at Belarus, Turkey, Tajikistan, Macedonia, Mauritius and Morocco, and declined in Mexico, according to data on the International Monetary Fund's website. Turkey's holdings increased to 5.758 million ounces from 4.429 million ounces and Mexico's declined to 3.413 million ounces from 3.417 million ounces in October, the data showed. Morocco's holdings were 710,000 ounces in November compared with 708,800 ounces in October, according to the data.

Gold gained 10 percent in 2011, rallying for an 11th year, as investors bought gold to protect their wealth from market volatility due to the Euro zone debt crisis.

"The outlook for 2012 for gold and silver is not very bullish and rallies should be sold," said Kunal Shah, head of commodity research at Mumbai-based brokerage Nirmal Bang Commodities Pvt. "The strength in the dollar, slack demand from India and China are seen negative for gold prices."