US jobless claims fell to a nearly four-year low, the government said, but the report was skewed by seasonal factors while weak June sales at top retailers may bode ill for consumer spending.

First-time claims for state unemployment insurance benefits plunged 39,000 to 310,000 last week, the Labour Department said. It was the lowest level for claims since 302,000 in the week ended October 8, 2000.

A Labour Department official said the seasonal adjustment method used to calculate the data had anticipated a surge in claims for automakers' annual summer maintenance closures, but that rise did not occur in the week expected.

He said July is often a volatile month for claims overall. Economists said the seasonal adjustment issue made it hard to draw broad conclusions from the fall, which was much steeper than the drop to 345,000 anticipated in a Reuters poll.

"On the surface it looks like a good report but I would take that with a grain of salt because of this disentanglement with the seasonal adjustment factors," said Rick Egelton, deputy chief economist of BMO Financial Group in Toronto.

Meanwhile, major US retailers posted disappointing June sales, with Wal-Mart Stores Inc. generating its smallest monthly sales gain in more than a year as cool weather hurt summer merchandise demand.

Analysts say it is too soon to tell if weak June sales mean slowing consumer spending, but if demand does not pick up with warmer weather in July, earnings forecasts could be in jeopardy. Wal-Mart and Target Corp. offered modest sales forecasts for July.

"Is it simply weather? We know from the Weather Service that the month was cooler and wetter than normal, so that cut into the seasonal demand, but we also know from Wal-Mart that they were very much affected by gasoline prices," said Michael Niemira, chief economist for the International Council of Shopping Centers.

Consumer debt loads climbed in May by a larger-than-expected $8.2 billion, the Federal Reserve said in a Thursday report that also revised up April's credit increase to $5.3 billion from an originally reported $3.9 billion rise.

The May rise was led by non-revolving debt, which includes fixed-term loans for cars, boats and tuition expenses.