Wal-Mart Stores Inc. (WMT) Monday said June sales at stores open at least a year were tracking "around" the low end of its forecast, signaling that sales could miss its expectations.

The world's biggest retailer made no change to its forecast for a 4 percent to 6 percent increase in June same-store sales, but Wal-Mart uses the word "around" to show that sales growth could be slightly below its forecast range.

On a recorded message updating sales through June 18, Bentonville, Ark.-based Wal-Mart said sales slowed over the June 12-13 weekend but pickedon Father's Day gifts this year, down from $99.65 last year.

The trade group said high fuel prices may be hitting spending because customers have to shell out more for gasoline. Wal-Mart has long said that steep petroleum prices act as a tax on its shoppers and hurt sales.

In its weekly update, Wal-Mart also said spending increased after people received mid-month paychecks, suggesting that household budgets remain tight despite a recovering economy.

The best-selling categories last week included food, hardware, paper goods, pet supplies and toys.

Wal-Mart noted that the July 4 holiday lands in the July sales reporting period, but last year it counted in the June period. The retailer repeated its forecast that the shift in July 4 reporting periods will shave just under 1 percentage point from June same-store sales.

Wal-Mart shares were down 25 cents at $55.37 on the New York Stock Exchange (search).