NEW YORK -- The national average retail price of regular gasoline rose 6.8 cents a gallon to $3.591 a gallon in the week ended Monday, the Energy Information Administration said Tuesday.

Release of the price report was delayed by a day due to the Presidents Day holiday on Monday.

Prices are the highest since Sept. 19.

Pump prices have gained 20.2 cents, or 6%, over the past four weeks. With gain in eight of the last nine weeks, prices are up 36.2 cents a gallon, or 11.2%, since Dec. 19.

Gasoline futures on the New York Mercantile Exchange settled Tuesday at the highest level since July 29. The reasons: stronger crude oil prices and concerns of tightening supplies, due to both operating snags at some refineries and by operators' plans to shut down some East Coast refineries and overseas plants that also serve the region.

Gasoline prices are 40.2 cents, or 12.6%, above where they were a year ago.

The price gains have come despite data showing gasoline demand has slumped to 11-year lows in recent weeks.

Nationwide retail prices are 12.7% below the record price of $4.114 a gallon hit July 7, 2008, the EIA data show.

The EIA, in its February Short-Term Energy Outlook, projected that the pump prices of regular gasoline would average $3.475 a gallon this month, a record for February, and compared with $3.211 a gallon a year ago. So far, gasoline prices are averaging $3.532 a gallon this month. The EIA forecast was based on crude oil prices averaging $100 a barrel in the month, up from $88.58 a year ago. So far this month, benchmark U.S. crude oil futures prices are averaging $99.94 a barrel, but prices settled Tuesday at $105.84, the highest since May 4.

The EIA said the crude price accounts for 80% of the cost of gasoline.

Prices rose in all regions, led by a 16.9-cent rise on the west coast, where prices were highest since June 6. A 20-cent rise in California prices fueled the west coast gain.

Wholesale prices in the Los Angeles market Tuesday morning were reported up 24 cents to a three-a-half-year high of $3.57 a gallon. Market participants said a combination of factors including reduced refinery operations, continued shutdown at BP's Cherry Point, Wash. refinery after a Feb. 18 fire, and exports to South America were behind the rise.

The AAA Daily Fuel Gauge Report said gasoline prices averaged $3.57 a gallon on Tuesday, up 5.7 cents from a week ago. The price is up 18.5 cents from a month ago and is 12.6% above a year ago.

-By David Bird, Dow Jones Newswires; 1-212-416-2141; david.bird@dowjones.com

--Ken Clark contributed to this report.