NEW YORK, Nov. 20 (Xinhua) -- Crude prices headed lower on Friday as the U.S. dollar gained strength versus the euro, reducing commodities' appeal as an alternative investment.

    Light, sweet crude for December delivery fell 74 cents to settle at 76.72 dollars a barrel on the New York Mercantile Exchange. As December contract expires on Friday, the more active January contract lost 58 cents to settle at 77.47 dollars a barrel.

    U.S. currency rose for the third time in the past four days, boosted by lower risk appetite and weaker European economic data. A firmer dollar tends to sink crude because oil is priced in the greenback around the world.

    Meanwhile, Wall Street fell for the third day in a row, as concern grew that the rally has outpaced the prospects for economic growth, dragging oil lower.

    In London, Brent Crude for January delivery gave up 33 cents to77.31 dollars a barrel on the ICE Futures exchange.