McDonald's has started rationing chips in Japan due to a shortage of imported potatoes.
The company said it will only serve small portions of chips for the foreseeable future starting today following an industrial dispute in the US, which has restricted access to potatoes.
"Unfortunately without this sales restriction step, we would run the danger of running out of fries at some of our stores around the end of the year or beginning of the new year," a spokesperson added.
McDonald's said it has taken emergency steps to secure supplies, transporting 1,000 tonnes of frozen potatoes by air and shipping 1,600 tonnes using alternative routes from the West Coast.
But the shipment is expected to arrive in late January or early February, leaving the chain scrambling to find ingredients.
The shortage follows a long-running dispute between dockworkers and shipping lines at 29 ports along west coast of the United States.
McDonald's declined to comment on whether the changes will impact profits in the country, where it operates more than 3,000 restaurants.
The price of a medium-sized Big Mac meal including chips will be reduced to Y619 (£3.5) from Y669 to reflect the smaller portions.
The shortage of potatoes adds to McDonald's woes in the region where it was recently hit by a food scare in China after a supplier was accused of selling rotten meat and falsifying expiry dates.
Sales were down 4 per cent in November.Reuse content