American customers are switching to salad snacks

The figures are confirmation that in its home market the burger chain's strategy of promoting new, healthier foods such as salads is pulling in customers.

But in Japan, the firm's tofu-burger strategy appears to be meeting with less success: McDonald's Japan issued a profit warning on Friday, slicing 47% off its full year profit forecast.

US sales at stores open at least a year jumped 10% in July against the same month last year, the group said late on Thursday.

Across the McDonald's group as a whole, underlying sales rose 4.2%.

Profit warning

Japan-based McDonald's Holdings - half-owned by the US group - said it now expects net income of 2.10bn yen ($17.64m) in 2003, rather than 3.96bn yen predicted previously.

The Japanese firm cut its revenue forecast for 2003 to 303.4bn yen from its previous estimate of 328.3bn. It recently introduced price rises.

McDonald's last week pointed to higher sales as proof of its success in launching a revival in the group's overall fortunes, although it has not yet achieved an upturn in profits.

The group reported a fall in profits - to $471m (�290m) in the three months to end-June, from $498m a year earlier.

But it said it was encouraged by an 11% jump in sales.

It attributed falling profits to the high costs of restructuring its business, including the closure of hundreds of restaurants and investment in new products.