Gold edged lower on Thursday, as investors stood on the sidelines and awaited a key Spanish debt auction later in the day amid worries the euro zone debt crisis could flare up again.    

Concerns about Spain's finances and banking sector pushed up safe-haven U.S. Treasuries and German Bunds in the previous session, and caution prevailed in most markets.       

Gold, though traditionally seen as a safe haven during times of economic and political turmoil, has moved largely in tandem with riskier assets and against the dollar recently.     

Spot gold inched down 0.1 percent to $1,639.46 an ounce by 0627 GMT. U.S. gold was nearly flat at $1,640.50.    

"The upside is very heavy because the euro remains under pressure and the weak physical demand isn't helping," said Peter Fung, head of dealing at Wing Fung Precious Metals in Hong Kong.    

"We might see prices test $1,600 level, which will attract some physical buying interest."    

Technical analysis suggested that spot gold could fall towards $1,611.80 an ounce during the day, said Reuters market analyst Wang Tao.    

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