Oil prices dropped as traders focused on economic stimulus concerns surrounding the United States and China, the world's two biggest consumers of crude. Brent North Sea crude for delivery in August shed 73 US cents to stand at $US100.18 a barrel in late London deals. New York's main contract, West Texas Intermediate light sweet crude for August, was down five US cents at $US93.62 a barrel. Gold, silver and platinum slumped to multi-year lows as investors dump the precious metals on the belief that rising US interest rates and a cash crunch in China will limit demand. The most actively traded gold contract, for August delivery, on Monday fell $US14.90, or 1.2 per cent, to settle at $US1,277.10 a troy ounce on the Comex division of the New York Mercantile Exchange. Silver for July delivery fell 2.3 per cent to settle at $US19.493. Both settlements were the lowest since September 2010. Platinum for July delivery slipped three per cent, to $US1,329.10 a troy ounce, the lowest since October 2009. Metals were pressured by worries about a liquidity squeeze in China after the central bank there indicated it wouldn't take decisive steps to ease tight credit conditions. Copper closed at its lowest level in almost three years on the London Metal Exchange (LME), as investors cash out of base metals amid a continuing credit squeeze in top metals consumer China. At the PM kerb close on Monday, LME three-month copper was 2.2 per cent lower on the day at $US6,670 a metric ton. The metal earlier tumbled 3.0 per cent to $US6,613 a ton, its lowest price since July 2010. Aluminum closed 1.2 per cent lower at $1,771 a ton.