NEW YORK (CNN/Money) -
A retail trade group is blaming the hit movie "Shrek 2" for eating into retail sales last week.
The International Council of Shopping Centers said its weekly sales report showed retail sales fell 0.5 percent in the week ended May 22, compared to the previous week, which saw a fall of 0.8 percent.
Compared with the same week a year ago, sales rose 5.5 percent, but that was down from the 6.2 percent growth pace of the preceding week.
"As potential shoppers flocked to the theaters, chain-store sales were a little less robust," Michael Niemira, chief economist and director of research for the ICSC, said in a statement.
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"Shrek 2," an animated comedy about a green ogre, took in a record $128.9 million in ticket sales at U.S. theaters during the five-day opening that started last Wednesday, according to a report from trade publication Daily Variety.
But retail analysts said they doubted that Shrek or any other movie could hurt retail sales.
"It gets people out of their homes and closer to stores. You would think it would boost sales," said Frank Badillo, economist with market research firm Retail Forward.
He said the volatility in the weekly number could mean there isn't any one reason for the slight dip last week.
Retailer analyst Kurt Barnard said he also had doubts about a negative impact from "Shrek 2", and cited another possible factor: rising gasoline prices.
"It doesn't make sense to me," he said. "One of the reasons very clearly why retail sales were a little short of expectations, people have somewhat less money in their pocket from filling the tank."
Despite two consecutive weeks of falling sales, ICSC raised its forecast for comparable store sales in May to a 5 percent pace compared with May of last year, up from its an earlier forecast of a 4.5 percent gain.
The ICSC-UBS Weekly Chain Store Sales Snapshot is compiled from a group of major discount, department and chain stores across the country that report weekly results.
A separate reading of sales from Redbook Research, an independent company, found sales at major retailers rose by 4.1 percent on a year-over-year basis for the week ended May 22, down from the preceding week's 4.8 percent gain.
It attributed the slowdown in growth to inclement weather in the Midwest and the Memorial Day holiday falling later in the month this year.
Redbook said there was some good news for retailers, including customers paying full price for spring and summer apparel as well as for suits and dresses.
Reuters contributed to this report