NEW YORK, United States (AFP) — They are beloved by generations of early readers for their wacky rhyming tales and mischievous plotlines, but six Dr Seuss books are being pulled because of imagery now considered racist.

Dr Seuss Enterprises — the publisher of the bestselling children's books — announced Tuesday that it is taking the six titles, which include "If I Ran the Zoo" and "The Cat's Quizzer," out of print.

The move comes as criticism grows in the United States over the way minority communities have been portrayed in many of the author's books.

Dr Seuss Enterprises said it had made the decision after carrying out a review of its collection last year with the help of experts, including teachers.

"These books portray people in ways that are hurtful and wrong," the company said in a statement.

The other titles being consigned to history are "And to Think That I Saw It on Mulberry Street," "McElligot's Pool," "On Beyond Zebra!" and "Scrambled Eggs Super!"

"Ceasing sales of these books is only part of our commitment and our broader plan to ensure Dr Seuss Enterprises' catalogue represents and supports all communities and families," the statement added.

Dr Seuss Enterprises made the announcement on what would have been the birthday of the famous children's book author. 

Seuss, born Theodor Seuss Geisel in Massachusetts in 1904, published more than 60 books during his lifetime, including some of the most popular children's books of all time.

His most famous works include "The Cat in the Hat," "Green Eggs and Ham" and "How the Grinch Stole Christmas." He died in 1991.