U.S. chain store sales rose in the latest week on Easter-related purchases and mild weather, according to two reports issued Tuesday.

Sales advanced 1.1 percent in the week to April 15 after rising 1.8 percent the previous week, according to the International Council of Shopping Centers and UBS Securities.

The ICSC report said sales grew 4.0 percent last week compared with the same week in 2005. In the previous week sales rose 3.9 percent versus the same week a year earlier.

This year's Easter holiday fell three weeks later than in 2005, which, combined with warm weather, boosted sales in the first half of April, but a resurgence in energy prices could hurt sales later this month, said Michael P. Niemira, ICSC's chief economist and director of research.

"A worry for the second half of April is the recent rapid rise in energy prices," Niemira said.

A separate report from Redbook Research showed chain store sales at large U.S. general merchandise retailers rose 5.3 percent in the same week, compared to the same week last year.

The Johnson Redbook Index is a sales-weighted index of year-over-year same-store sales growth in a sample of large general merchandise retailers representing about 9,000 stores.

Crude oil prices have soared from $20 a barrel in early 2002 to near the inflation-adjusted peaks of over $80 in 1980, the year after a revolution toppled the Shah of Iran.

U.S. retail unleaded gasoline averaged $2.78 a gallon in the week to April 17, the highest since Oct. 10, 2005 when prices averaged $2.85, the U.S. Energy Information Administration said.

Early Tuesday, U.S. gasoline futures for May delivery posted a contract high of $2.181 a gallon, up nearly 16 percent so far in April.

The spike in gas prices fanned worries consumers would cut spending, crimping economic growth. Consumer spending accounts for at least two-thirds of U.S. economic activity.

Higher gasoline prices have not slowed U.S. retail sales by much, however. Niemira forecast unadjusted store sales would grow 5.5 to 6.0 percent in April, well ahead of expectations and March's 2.0 percent increase.