WASHINGTON — Oil prices jumped to a record yesterday as investors continued to fret about tight supplies even after OPEC announced it would pump more oil later this year.

The price of a barrel of light, sweet crude oil for delivery in October rose 74 cents to $78.23. That was the highest price, not adjusted for inflation, on record, beating the previous mark of $78.21 set July 31. Adjusted for inflation, the record price was nearly $93 a barrel set in January 1981.

Oil prices have risen 9.5 percent in the past month as investors worry about a tight balance between supply and demand worldwide. Energy Department analysts in a monthly report yesterday warned that balance will remain tight for some time, reflecting increased demand and supply constraints.

"Barring a slowdown in oil demand growth, continued high demand and low surplus capacity leave the market vulnerable to unexpected supply disruptions through 2008," they wrote.

OPEC members pledged yesterday to raise production by 500,000 barrels a day starting Nov. 1. But investors were not impressed.

"The market was looking for more than 500,000 barrels a day," says Kevin Lindemer, head of the energy group at Global Insight.

For consumers, the higher oil prices will likely not show up at the gasoline pump, Oil Price Information Service analyst Tom Kloza says. That's because gas demand is declining, and refineries are producing at healthy rates. The nationwide average price for a gallon of regular gasoline was $2.814 yesterday, down a fraction of a penny from Monday but still up 19 cents from a year ago, according to motorist club AAA and OPIS.

But the higher oil prices will likely be seen in other energy costs, including diesel and jet fuel and heating oil, Kloza says.

"Maybe you are paying less at the pump, but you're going to pay more for an airline ticket or to mail your boxes," he says.

Retail heating oil prices are projected to average $2.78 a gallon from October through March versus $2.48 last winter, the Energy Department said.