Harry Potter used in worldwide appeal to help find missing Madeleine

Posters of Madeleine will be made available to booksellers in more than 200 countries around the world.

Rowling will personally ask the bookshops to display the posters around July 21, the publication date of the long-awaited final book in her best-selling series, to raise the profile of the hunt for the missing girl.

Four-year-old Madeleine has not been seen since she disappeared from a holiday apartment in Praia da Luz, Portugal on May 3.

Rowling has been moved by the plight of the McCann family and agreed to help the Find Madeleine campaign when asked for her support.

She hopes thousands of people around the globe will see the missing girl's image as they queue up to buy their copy of Harry Potter and the Deathly Hallows.

She said yesterday: "I fervently hope that posters displayed prominently in shops all over the world when the new book comes out will help find Madeleine McCann and will help raise the profile of the many other missing children in different countries."

The posters show three different pictures of Madeleine, above the message: "If you have seen me, please contact your local police agency!"

The posters also give the website address for the International Centre for Missing and Exploited Children. Rowling is asking bookshops to display the pictures through her 65 international publishers.

The McCann family said they were delighted that the Harry Potter author is launching the posters.

Madeleine's mother, Kate McCann, said: "We are overjoyed by this generous offer and would like to thank JK Rowling, her publishers and book retailers for all they are doing to help.

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"Madeleine has the first three Harry Potter books and first three DVDs. Like most other children the world over, she loves the stories."

Rowling has already pledged money towards the reward fund for information leading to Madeleine's recovery. She and her publishers originally planned to print bookmarks with Madeleine's image which could be inserted into copies of the new book.

But the idea was shelved after they decided it would not be responsible to expose younger readers to the story of Madeleine's disappearance.

The writer has also provided a link to the findmadeleine.com website from her own website jkrowling.com, which receives between three and seven million hits per day.