(Reuters) - Louisiana was sued on Monday over a new law requiring the display of the Ten Commandments in all public school classrooms in the state.

The complaint said displaying the Ten Commandments violates the First Amendment of the U.S. Constitution, and "simply cannot be reconciled with the fundamental religious-freedom principles that animated the founding of our nation."

Governor Jeff Landry, a Republican, said when signing the law on June 19 that requiring the display would help expand faith in public schools. Louisiana became the only U.S. state with such a requirement.

"If you want to respect the rule of law, you've got to start from the original law-giver, which was Moses," Landry said at a signing ceremony.

(Reporting by Jonathan Stempel in New York; Editing by Josie Kao)