Kensuke's Kingdom by Michael Morpurgo has won the Children's Book Award, preventing Harry Potter creator JK Rowling from collecting the prize for a third time.

A veteran storyteller, Mr Morpurgo, 57, is the author of more than 60 children's books and winner of numerous awards, including the Whitbread Children's Book Award.

Kensuke's Kingdom, which also scooped the best shorter novel prize, is a children's story in the traditional mould and features a desert island.

Mr Morpurgo said: "Two of my favourite books are Treasure Island and Robinson Crusoe so it's no accident that I've written books about islands.

"I've always wanted to write my very own desert island story."

The author has been a tireless campaigner for children's literature and, together with the late Ted Hughes, was responsible for establishing the post of Children's Laureate.

He also runs the charity Farms for City Children which enables youngsters from the inner cities to experience life on a working farm.

Prize for Potter

Mr Morpurgo was presented with the award by Ana Boulter of Children's BBC, after signing copies of his book for around 100 children who attended the ceremony at the Kensington Roof Garden in central London.

Nicholas Allan won the picture book category with The Demon Teddy.

JK Rowling may have missed out on the top award but she still had something to smile about as Harry Potter and the Prisoner Of Azkaban won the best longer novel category.

In January, the wizarding tale scooped the Whitbread Children's Book of the Year 1999 award - that time beating Kensuke's Kingdom.

The Children's Book Award, organised by the Federation of Children's Book Groups, is unique in that votes are cast solely by children.

This year, about 20,000 youngsters took part in the judging of some 1,200 books.