World oil prices fell in volatile Asian trade on Thursday after rising earlier following a US government report that showed American crude reserves dipped for the fourth week in a row. New York's main oil futures contract, light sweet crude for July delivery, was 1.12 dollars lower at 135.26 dollars a barrel after trading as high as 136.99 in the morning. The contract jumped 5.07 dollars to close at 136.38 on the New York Mercantile Exchange on Wednesday. "It could be a volatile time," said David Moore, a commodities strategist at the Commonwealth Bank of Australia in Sydney, commenting on the reversal of prices after earlier gains.