NEW YORK — Speculators boosted bets that gasoline prices will rise on prospects for the most Independence Day traffic in seven years and fighting in the Middle East.

Money managers increased net-long positions by 7.6 percent in the week ended June 24, U.S. Commodity Futures Trading Commission data show. Long positions advanced 5.5 percent and shorts fell 0.3 percent.

Americans traveling by car over the July 4th weekend will pay the most for fuel since 2008, AAA said last week.

Pump prices are at the highest level for the period in six years, data from the motoring organization show. Gasoline advanced with crude this month after Islamist insurgents captured the northern Iraqi city of Mosul and advanced toward Baghdad.

Gasoline gained 1.1 percent to $3.1258 a gallon on the New York Mercantile Exchange, the CFTC report said.