Gasoline futures surged nearly 7 percent Tuesday on word of a large refinery snag, marking an almost 50-cent-per-gallon increase over the past month that is sure to send pump prices higher.

The average retail price of unleaded gasoline was $2.37 a gallon last week – the highest level since November, according to the Energy Department.

Gasoline futures rose 12.27 cents to settle at $1.866 a gallon on the New York Mercantile Exchange.

Brokers said the rally was sparked after Amerada Hess Corp. said Tuesday that over the weekend it unexpectedly shut a gasoline producing unit at a refinery in St. Croix that it co-owns with Petroleos de Venezuela SA.