The posters must be on display in all classrooms receiving state funding by 2025 - but no state funding is being offered to pay for the posters themselves.

Similar laws have recently been proposed by other Republican-led states, including Texas, Oklahoma and Utah.

Four civil liberties groups have confirmed that they plan a legal challenge, highlighting the religious diversity of Louisiana’s schools.

The law was “blatantly unconstitutional”, said a joint statement from the American Civil Liberties Union, the American Civil Liberties Union of Louisiana, Americans United for Separation of Church and State, and the Freedom from Religion Foundation.