Oil prices fell sharply to around US$63 a barrel Friday amid weakening global demand for crude - despite a decision by the OPEC cartel to cut production quotas by 1.5 million barrels a day from next month. Light, sweet crude for December delivery fell $4.69 to $63.15 a barrel in electronic trading on the New York Mercantile Exchange by mid-afternoon in Europe. Prices had fallen as low as $62.85. The contract overnight rose $1.09 to settle at $67.84. The size of the OPEC cut reflected concerns within the Organization of Petroleum Exporting Countries, which accounts for 40 percent of global oil supply, that the bottom appears to be falling out of the market. Crude is selling for 50 percent less than this year's historic heights because the worldwide economic crisis has put a huge crimp in demand.