Brent crude oil futures fell below 49 dollars a barrel, today, giving up part of this month's strong rally, as signs of rising supply outweighed hopes that producing nations will agree steps to support prices. Brent crude was down 59 cents, at 48.57 dollars a barrel. Brent had rallied 20 percent between the beginning of the month and August 19. U.S. crude was down 62 cents, at 46.79 dollars a barrel. Investment bank, Goldman Sachs said in a report, that talk of an output freeze by the Organization of the Petroleum Exporting Countries and a weak dollar had helped drive prices up this month, but neither was enough to sustain current levels.