(Reuters) - U.S. diner chain Waffle House has added a 50-cent surcharge for every egg in a customer's order, the company said in a statement posted in its restaurants on Monday.

The fee is temporary, the company said in a statement Tuesday, and is a response to a "dramatic increase in egg prices" caused by bird flu outbreaks.

"While we hope these price fluctuations will be short-lived we cannot predict how long this shortage will last," the statement read. 

The privately-held chain is known for its low prices. A standard American breakfast with two eggs is sold for $7.75 in Norcross, Georgia, where the company is headquartered. That meal is now $1 more expensive.

The price of U.S. wholesale eggs hit an all-time high in December, according to commodity data firm Expana, with a dozen eggs going for $5.57 in the Midwest and $8.85 in California.

The main factor driving egg prices higher is damage to the laying flock from bird flu. The virus wiped out more than 20 million chickens in the U.S. last quarter, data from the U.S. Department of Agriculture shows, the highest toll since the beginning of the outbreak in 2022.

The chain said it has 2,100 locations across the United States. Its website says it serves 272 million eggs every year.

(Editing by Nick Zieminski)