LONDON (AFP) - World oil prices edged higher on Tuesday after US forecasters issued a hurricane warning for the Gulf of Mexico where many US energy facilities are based, traders said. The warning came as Tropical Storm Dolly swirled through the Gulf. Brent North Sea crude for September delivery added nine cents to 132.70 dollars per barrel in London trade. New York's main contract, light sweet crude for August delivery, gained six cents to 131.10 dollars a barrel. "Dolly is one of the factors" for higher prices, said Ken Hasegawa, a broker at Newedge Japan. "The situation is not so serious at the moment, but (the storm's) direction is hard to predict." The market had rebounded on Monday, after falling by more than 16 dollars last week, as Dolly bounded into the Gulf of Mexico and the international community tightened pressure on oil producer Iran to halt its nuclear programme. "The storm, whilst not yet a hurricane, has potential to threaten some Mexican production facilities in the Bay of Campeche," added analysts at the John Hall Associates consultancy. "At this time it is expected that US facilities towards the east are expected to escape the trajectory." Forecasters issued a hurricane warning on Tuesday as Tropical Storm Dolly threatened to grow into a hurricane within 24 hours near the Mexico-Texas border. "A hurricane warning is in effect for the coast of Texas from Brownsville to Port O'Connor," the Miami-based National Hurricane Center said at 0600 GMT. "A hurricane warning is also in effect for the northeast coast of Mexico from Rio San Fernando north to the border with the United States." The warning means hurricane conditions are expected in the area in the next day. At 0600 GMT, the center of the storm was about 320 miles (515 km) southeast of Brownsville, Texas, as it moved westward near 17 mph (28 km/hr), the NHC said, noting that "the center of Dolly should be very near the western coast of the Gulf of Mexico on Wednesday." It was packing maximum sustained winds near 50 mph (85 km/hr) with higher gusts. US energy major ExxonMobil has started evacuating "non-essential" personnel from some offshore oil production facilities expected to be in Dolly's path, but the company said there had been limited impact on production thus far. Chevron and Royal Dutch Shell have also moved non-essential staff from their operations in the western part of the Gulf of Mexico. Investors are also watching closely for any developments in the Iran nuclear talks aimed at getting Tehran to halt its uranium enrichment programme, dealers said. Weekend talks in Geneva made little progress and Iran has two weeks to respond seriously to an international offer to halt its sensitive nuclear work, which the US and other major powers suspect is for making weapons. Tehran insists its uranium enrichment programme is for civilian purposes. Iran, the number two oil producer in OPEC, reaffirmed on Tuesday that it was against any hike in the cartel's output quota despite continued high crude prices. "The market is in a good situation," Oil Minister Gholam Hossein Nozari told reporters in Tehran on the sidelines of a petrochemical conference. "In the next OPEC meeting we are heading towards winter. I think that preserving the current situation is the most appropriate one," he added. The Organization of Petroleum Exporting Countries was scheduled to hold its next regular meeting on September 9 in Vienna, where OPEC is headquartered.