Wal-Mart, the largest US retailer, said on Thursday that its customers were increasingly feeling the pressure of higher fuel prices, as it reported that comparable sales at its discount stores increased by just 1.1 per cent during June.

Tom Schoewe, chief financial officer, said research among Wal-Mart’s predominantly lower income shoppers showed increasing concern about the rise in petrol prices over the past year.

Wal-Mart’s customers, he said, were consolidating shopping trips to cut down on driving, and reducing non-essential purchases. “The priority in spending by our customers is on food and consumables,” he said.

Other smaller discounters also reported lower than expected sales at stores open at least a year, although Target, Wal-Mart’s more upmarket rival, reported a strong 4.8 per cent gain in June sales.

Ken Perkins, president of Retail Metrics, said he saw signs of weakness at discounters “across the board” in June as low income customers faced higher driving costs. “We would expect that to continue to the second half, with no sign of an easing of gas prices”.

A separate survey of US shoppers’ sentiment by Retail Forward consultants also raised questions on Thursday about the strength of consumer demand among wealthier US households, which account for the bulk of retail spending.

Steve Spiwak, an economist at Retail Forward, said the monthly Future Spending index, based on a survey of 4,000 households, showed signs of increasing pressures that went beyond gasoline prices affecting households with incomes above $22,000.

“In particular, the drag of debts amid rising interest rates is taking a bigger toll on household cash flow. The recent stock market downtrend and concerns about income growth also are crimping the desire to spend.”

Retail Metrics’ overall monthly same-store sales index from leading retailers for June showed a 2.8 per cent gain, below the 3 per cent expected by Wall Street industry analysts.

But Mr Perkins said sales had remained surprisingly resilient, despite both high fuel prices and the impact of heavy rains and flooding in the north-east US that further depressed demand.

“I’m amazed at the American consumer’s ability to spend,” he said, suggesting that reported strength in the jobs market could hold up retail demand in the coming months.

“As long as the job market holds up, there’ll be some floor for consumer spending and we’re not going to see the slowdown we’ve been expecting.”