Kate McCann publishes her fundraising book called Madeleine later this year

 FORMER Portuguese police chief Goncalo Amaral is set for a new legal battle with Kate and Gerry McCann after writing a second book about their missing daughter Madeleine.

Mr Amaral's book will be published in Portugal next month shortly before Kate McCann publishes her fundraising book called Madeleine.

It could not come at a worse time for Kate, 42. She is hoping someone who reads her book will come forward with information about the person who took her daughter on May 3, 2007.

The McCanns' private investigator David Edgar is also preparing to beef up his team in Portugal to react swiftly to any new leads produced by Kate's book. It goes on sale in Britain on May 12 and a week later in Portugal.

The McCanns have already fought a costly legal battle over Mr Amaral's first book on the case. Called Maddie: The Truth Of The Lie, it was taken off the shelves for several months before being allowed back on sale.

On Friday the McCanns lost an appeal in Portugal's Supreme Court to stop his first book from going back on the shelves there.

In the book Mr Amaral put forward the theory that Madeleine had died in apartment 5a of the Ocean Club complex in Praia da Luz on the Algarve. His conclusion angered the McCanns, who insist there is no evidence to suggest Madeleine died there and they still hope she is alive.

Now the stage is set for a fresh legal battle. Mr Amaral's wife Sofia said: 'Goncalo has been working on his book for about six months, spending days and nights assessing all the evidence. He has put in an enormous amount of work. The title has not been decided and a publication date will be sorted out this week.

'At this stage he doesn't want to say too much, but he will say his investigation was cut short and he will explain what he would have done if he had been allowed to continue. The book is not just about Madeleine. He gives the background to other big cases he was involved with

'The timing of this new book is just coincidental, nothing was planned. We are not trying to cash in on the fourth anniversary of Madeleine's disappearance and we do not want a fight over Kate's book.'

Mr Amaral was a senior investigation officer in the case but was taken off it after criticising British police for an alleged lack of co-operation.

After resigning from the Policia Judiciaria, he has become a successful author in Portugal and regularly appears on television news. He has tried to publish The Truth Of The Lie in Britain but no publisher has accepted it for fear of being sued for libel.

Kate McCann is said to have been warned by her publisher to be careful of what she says about Mr Amaral. However, she does chronicle her frustration with him and her anger over the way he looked at the case.

The Sunday Express can also reveal that Mr Edgar has been making regular trips to Portugal to check out leads in recent months.

A source said: 'The investigation is very active. There is a hope that Kate's book will lead to someone coming forward with the key piece of the jigsaw.'