Supermarkets and restaurants have had to throw away tons of vegetables, meat and dairy products after a massive power cut hit parts of North America.

"We have to throw out any kind of product whose integrity could have been compromised," Rich Savner, a spokesman for Pathmark Stores, which operates more than 100 supermarkets in the New York, New Jersey and Philadelphia areas, was quoted as saying by Reuters.

Pathmark said it used 1,000 pounds of dry ice to try to prevent ice cream, milk and meat from spoiling.

A spokeswoman for grocery chain Stop & Shop said it was sorting through its stores to see what needed to be discarded. She said the company had sent refrigerated trucks to some stores to try to minimise the damage.

John Zimmerman, a spokesman for supermarket chain Meijer said around 25 stores in the Detroit area were operating with generators on Friday, while another six were closed, reported Reuters.