A broad sell-off in gold and silver accelerated on Friday as speculators took profits after the prices of both metals raced to their highest in more than two decades this week. As silver came under the hammer of sellers -- losing as much as 4 percent after a big tumble in the last COMEX session -- dealers predicted the metal would be hard-pressed to retest soon the $14-per-ounce-plus levels hit earlier this week Spot gold was last fetching $613.30/$614.10. That price is still up 18 percent this year, but was well under Thursday's high of around $645. Gold fell as low as $619.20/620.00 an ounce in New York after London's late fix was set at $625 before opening in Sydney at $611.50/$612.30 an ounce. "Gold and silver were certainly benefiting from speculative money and that was never going to be sustainable," Australia & New Zealand Bank commodities analyst Andrew Harrington said. Sharp declines in gold futures helped set the stage for sales in the spot market, with COMEX June gold falling by as much as $25 on Thursday. It settled at $623.10, off $12.90, or 2 percent.