KFC has apologized to its customers in the U.K. after branches of the fried chicken chain were forced to close because they've run out of chicken.

Taking to Twitter to explain the crisis, KFC said the shortage had been caused after it had taken on a new delivery partner, DHL, and apologized for the closures.

Tweet:

"We've brought a new delivery partner onboard, but they've had a couple of teething problems — getting fresh chicken out to 900 restaurants across the country is pretty complex!," the chain said in an online statement Monday.

"We won't compromise on quality, so no deliveries has meant some of our restaurants are closed, and others are operating a limited menu, or shortened hours."