The paperback version of Kate McCann's book Madeleine has topped the charts, selling 39,000 copies since it was released five weeks ago.

Her book about the abduction and continuing search for her daughter entered the paperback non-fiction chart at number two, climbing to number one for the second and third week of sale.

It is currently fourth in the league table, surprising industry experts.

Philip Stone, charts editor at The Bookseller magazine, said: "I was quite impressed.

"It was one of those books that I thought, if you wanted to read it, you would have wanted to read it when everyone was talking about it and when it was serialised in the paper – when the hardback came out.

"I thought that might mean the paperback would struggle. Shows what I know.

"It is one of the best-selling non-fiction paperback books of the last month."

At its peak, the paperback reached 13th place in the top 50 list of all books on sale, and sits at the 33rd position in that league table.

The book was released on May 11 – a year after the hardback version became one of the fastest-selling non-fiction books since records began in 1998.

It sold about 73,000 copies in the week of its release. Only five other non-fiction books have registered stronger sales in their first week – two cookery books by Delia Smith, the autobiographies of David Beckham and Tony Blair and a book by Princess Diana's former butler, Paul Burrell.

The 496-page paperback book has been published by Corgi, and is on sale for £7.99.

All the proceeds from sales will go towards the search for Madeleine, who went missing, aged three, during a family holiday to the Portuguese resort of Praia de Luz in May 2007.

The official Find Madeline Campaign took part in The Big Tweet, run by the Missing Children charity, last month.

For a whole day, on May 25, the charity tweeted messages dedicated to each missing child in the UK – including Maddie – and via the campaign website Kate McCann encouraged Twitter users to repost the messages to their followers.

On Wednesday, the campaign's Facebook page also urged holidaymakers to print off special translated posters about Maddie, in the language of their destination country, to distribute while on holiday.

A message on the campaign website said: "Going on holiday? Please take a holiday pack to raise awareness and to keep people looking for Madeleine.

"The vital piece of information that leads to a happy and longed-for reunion is usually thanks to a caring and vigilant member of the general public, often recognising a face from a poster. It is for this reason that we must continue to remind people of Madeleine and the fact that she is still missing." 

http://findmadeleine. com/home.html