Platinum climbed to the highest level in more than 16 months, widening its premium over gold to the most since 2011, on concern that supplies will decline from South Africa, producer of about 73 percent global output.

Platinum for immediate delivery rose as much as 0.3 percent to $1,742 an ounce, the most expensive since Sept. 22, 2011, and was at $1,741.87 by 2:33 p.m. in Singapore. Spot gold rose 0.2 percent to $1,680.65 an ounce. The gap at $61.22 is the widest since August 2011, according to data tracked by Bloomberg.

Upheaval has plagued producers in South Africa since August last year, when thousands of workers staged a series of illegal strikes, winning pay increases. Nine loss-making mine shafts were shut in the second half of 2012, according to government data, while Anglo American Platinum Ltd., the largest producer, last month announced plans to idle four shafts. World output will drop 2.7 percent to 5.68 million ounces this year, the least since 2000, according to Barclays Plc.

“Platinum is at the forefront of precious metals investors’ minds because of supply issues in the world’s biggest producer,” said Gavin Wendt, a senior resource analyst and founder of Mine Life Pty in Sydney. “There’s sound reasoning for people to be putting their money into platinum.”

Holdings in exchange traded-products backed by platinum stood at 51.45 metric tons Wednesday from a record 51.46 tons on Feb. 5, data compiled by Bloomberg show. One ounce of platinum bought as much as 1.0374 ounces of gold today, according to data tracked by Bloomberg.

Gold for April delivery was little changed at $1,681.10 an ounce on the Comex in New York. Cash bullion of 99.99 percent purity rose 0.3 percent to 338.02 yuan a gram ($1,685.47 an ounce) on the Shanghai Gold Exchange. Futures gained 0.2 percent to 30,771 rupees per 10 grams ($1,799.83 an ounce) on the Multi Commodity Exchange of India Ltd.

Spot palladium was little changed at $763.50 an ounce, while silver for immediate delivery was at $31.87 an ounce from $31.8325 Wednesday.