CAMARILLO, Calif. (AP) – Retail gasoline prices rose about a half-cent per gallon in the past two weeks as crude oil prices remained firm and demand increased because of the improving economy, an industry analyst said Sunday.

The average price Friday for a gallon of self-serve gas nationwide, including all grades and taxes, was about $1.55, according to the Lundberg Survey of 8,000 stations. That was up 0.53 cents since Nov. 7. It was 11.34 cents higher than the average on the same day last year.

The increase ended a two-month decline.

, during which prices slipped nearly 20 cents following the end of a supply crunch.

Prices are expected to rise moderately in the short term, but steeper increases are possible if the Organization of Petroleum Exporting Countries decides to cut production at its Dec. 4 meeting, or if there are “glitches” in the rollout next month of gasoline blends with the pollution-reducing additive ethanol, Lundberg said.

The national weighted average price of gasoline, including taxes, at self-serve pumps Friday was about $1.52 a gallon for regular, $1.62 for mid-grade and $1.71 for premium.

AP-ES-11-23-03 1731EST