US comedian Steve Martin has written a tongue-twisting children's book.

The actor, who has penned several novels and newspaper articles, created The Alphabet From A To Y With Bonus Letter Z! with cartoonist Roz Wilson.

But he admitted that he was unsure why he had turned his hand to writing for children, saying: "I don't know why an alphabet book popped into my head - my idea was to write these rhyming couplets with the craziest images I could possibly think up, and then have Roz illustrate them."

The book, described as a "nonsense ride across time and rhyme", allows youngsters to practice their language skills with the tongue-twisters such as N: "Needle-nosed Nigel won nine kinds of knockwurst / By winning a contest to see who could knock wurst".

Martin married earlier this year but has no children of his own. He follows in the footsteps of celebrity children's authors including Madonna, Billy Crystal, Jamie Lee Curtis, Jerry Seinfeld, John Lithgow and Geri Halliwell.