Retailers reported strong sales last week as shoppers took advantage of discounts and longer store hours for the start of the holiday shopping season.

The International Council of Shopping Centers said sales rose 1.7 percent last week, the biggest gain since June.

The ICSC surveys retail chain stores, but does not include sales of cars or meals at restaurants. It compares sales to the prior week.

Separately, the Johnson Redbook Index of large merchandise retailers showed sales rose 5.4 percent last week from a year earlier.

That left Redbook's month-over-month reading up 2.2 percent in November, the biggest monthly jump since November 2009.

Despite the attention paid to the start of the holiday season, economists warned that strong sales might not be a sign of a new trend.

Consumers may have pushed up spending to the beginning of the shopping season because of the steep discounts and longer store hours. With incomes stagnant and the jobless rate stuck at about 9 percent, consumers may pull back spending later in the season, economists warned.

(Reporting by Jason Lange; editing by Jeffrey Benkoe)