World oil prices fell sharply yesterday after an OPEC source said the US had asked the cartel to consider raising crude supplies in order to ease prices and help the U.S. economy after last week's attacks. Plummeting equity markets in the United States contributed to the negative sentiment, as concerns about a deepening of the global economic slowdown intensified. London futures for Brent crude oil last traded $1.05 weaker at $28.36 a barrel, after climbing earlier on escalating military tension on the border between Afghanistan and Pakistan. US oil futures fell 72 cents to $28.83 a barrel in a shortened session in New York. "Weak equities markets and requests for more OPEC oil has pushed the price down," said one broker.