Michael Jackson rehearses for the London concerts at the Staples Center in Los Angeles on June 23. (Kevin Mazur/AEG/Getty Images/Associated Press)

Montreal-born author Ian Halperin's new book Unmasked: The Final Years of Michael Jackson has been snapped up by a major French publisher, which will distribute 100,000 copies of the unauthorized biography.

In a stroke of synchronicity, the book, produced by Quebec's Transit Publishing, was already in the presses on the night Jackson died. It was timed to hit the shelves as Jackson was due to launch his London concert series.

Pierre Turgeon, Transit's director, confirmed to the Globe and Mail his company had sold the rights to French giant Hachette Livre.

Transit has already sold the U.S. rights to publisher Simon & Schuster and is in talks with a British company.

Canadian readers will have the opportunity to be the first to peruse the book, due out next week.

Halperin, who also penned an unauthorized biography of Cirque du Soleil founder Guy Laliberté, says his book is a "vindication" of Jackson in the face of accusations of child abuse he faced in the 1990s.

"We hope that this book will give him back his reputation as much as we can — his glory as an artist — because we feel that he had been destroyed morally, psychologically and also as an artist by all these accusations and by the way his entourage was pressuring him out of greed to do those London concerts," said Halperin in an interview earlier this week.

Halperin has also added more material to the book since Jackson's death June 25.

Authorities have launched an investigation into Jackson's death. A pathology report on the cause of death isn't due out for a few more weeks.

The sedative Diprivan, also called Propofol, was discovered in Jackson's home. It is a powerful anesthetic administered intravenously in operating rooms to induce unconsciousness.

As rumours swirl around Jackson's health at the time of his death, investigators are examining the possibility the singer used pseudonyms to acquire prescription painkillers, sedatives and antidepressants.

Madonna to pay an homage in London concert

Meanwhile, Madonna — a friend of the performer, who was 50 when he died — says she is preparing a special tribute to him.

Madonna spokesperson Liz Rosenberg says she is going to unveil a special song, along with a choreographed dance in honour of Jackson.

The singer will be performing at London's 02 arena on Saturday night — the same venue where Jackson was to do his comeback concerts, starting July 13.

In Los Angeles, officials are preparing for an onslaught of fans and media for Jackson's memorial, to be held at the city's Staples Center on Tuesday.

"You might want to consider watching this from the comfort of your own home," suggested Los Angeles City Councilwoman Jan Perry, who is also the city's acting mayor.

Assistant police Chief Earl Paysinger predicted on Saturday that anywhere from 250,000 to 700,000 people may try to get to the arena.

The ceremony, expected to start at 10 a.m. PT, will also be streamed online.

Fans have been told to register for free tickets on the Staples website. Some 8,750 names will be randomly selected and those people will be notified Sunday. Each person will get two tickets and wristbands on Monday.

Some half a million people had already registered by Friday evening.