Gas prices in United States up as Gustav threatens Gulf refineries (Oil-Prices)

NEW YORK _ Retail gas prices in the United States swung higher Friday _ the first increase in 43 days _ as analysts warned that a direct hit on U.S. energy infrastructure by tropical storm Gustav could send pump prices hurtling toward US$5 a gallon.Meanwhile, oil prices ended the day slightly lower, falling for a second straight session. But prices fluctuated sharply as some traders feared supply disruptions and others bet the government will release supplies from the Strategic Petroleum Reserve