Kate and Gerry McCann have urged the public to get behind the search for their missing daughter Madeleine as they did when she disappeared more than four years ago.
They also made a direct appeal to Prime Minister David Cameron for a full independent review of the shelved police investigation into what happened to the little girl.
The couple hope that Mrs McCann's highly-personal book about Madeleine's disappearance, which went on sale today, will revive efforts to find their daughter.
Mr McCann, 42, told ITV1 show Lorraine: "We want people to read the book because it puts what's happened to us and what we are doing in context.
"But more than anything, we want the public to get behind the search for Madeleine like they did in 2007."
Madeleine was three when she went missing from her family's holiday apartment in Praia da Luz in Portugal on May 3 2007 as her parents dined with friends nearby.
The official Portuguese inquiry into the disappearance was formally shelved in July 2008, although private detectives employed by the McCanns have continued the search.
Launching her book today on her daughter's eighth birthday, Mrs McCann, 43, said people were "understandably shocked" that the authorities had "essentially given up" on the child.
The McCanns, from Rothley, Leicestershire, have written to Mr Cameron asking for an "independent, transparent and comprehensive" review of all information about Madeleine's disappearance.
In an open letter published by The Sun, they told the Prime Minister: "Thus far there has been no formal review of the material held by the police authorities - which is routine practice in most major unsolved crimes.
"A key piece of the 'jigsaw' could easily have been overlooked and not joined up with another. We have tried in vain to get the authorities in the UK and Portugal to play their part.
"But, sadly, our requests have seemingly fallen on deaf ears. It is simply not acceptable that they have, to all intents and purposes, given up on Madeleine."
A spokeswoman for Mr Cameron said: "The Prime Minister met Kate and Gerry McCann while he was leader of the Opposition, and he has followed their plight very closely.
"He and the Home Secretary want to make sure the Government does all it can to help them".
Mrs McCann revealed that Easter Sunday this year marked the point when she and her husband had spent more time without Madeleine than with her.
Her book, titled simply Madeleine, racked up large advance sales and has been online giant Amazon.co.uk's top-selling book for several days.
A spokeswoman for publisher Transworld said there had been a "huge amount of early interest".
All proceeds will go to the McCanns' official fund to look for Madeleine, which had been in danger of running out this year.
Extracts from the book published in The Sun and the Sunday Times reveal Mrs McCann's torment at learning that her daughter had disappeared.
She writes: "When she was first stolen, paedophiles were all we could think about and it ate away at us.
"The idea of a monster like this touching my daughter, stroking her, defiling her perfect little body, just killed me over and over again."
Mrs McCann accuses Portuguese detectives of attempting to "bully" her into confessing to hiding Madeleine's body, and voices her fears that the "lovely" sight of her daughter in a new outfit may have led to her kidnap.
She also says the couple were nearly "pushed over the edge" by abusive letters in the wake of Madeleine's abduction, and described their reaction to "bile and hate" on the internet.
"In the early days this upset me tremendously, but gradually I grew a protective shell," she said.
The 384-page book was originally due to be published a fortnight ago but the publishers postponed the release date to avoid clashing with the royal wedding.
The ebook edition is available for download worldwide today and physical copies will be shipped to the US, Australia and New Zealand over the next week. It is also being translated into Portuguese and Spanish.