Kate McCann writes of how at times she wanted to swim out to sea and 'let the water relieve me of this torment'

Kate McCann has revealed that she was plagued with depression and suicidal thoughts after the abduction of her daughter Madeleine in Portugal four years ago.

In a new book chronicling Madeleine's disappearance and the toll it took on her family, McCann also writes of her pain at being branded a "cold, emotionless woman" because of the public face she put on during the investigation.

"It's quite frightening when I see myself in those early days," she writes. "To me I look incredibly fragile and confused and lost." Despite appearing to be brave and composed, she says, she was on the verge of a breakdown.

"I had an overwhelming urge to swim out across the ocean, as hard and as fast as I could; to swim and swim and swim until I was so far out and so exhausted I could just allow the water to pull me under and relieve me of this torment," she writes.

"I wasn't keeping that desire to myself, either. I was shouting it out to anyone who happened to be in the room. Both this urge and the expression of it were, I suppose, an outlet for the crucifying anguish.

"Somehow, inflicting physical pain on myself seemed to be the only possible way of escaping my internal pain."

McCann also reveals that she was tormented by "a macabre slideshow of vivid pictures in my brain" as she tried to imagine what might have happened to her three-year-old daughter.

"I was crying out that I could see Madeleine lying, cold and mottled, on a big grey stone slab. Looking back, seeing me like this must have been terrible for my friends and relatives, particularly my parents, but I couldn't help myself."

In excerpts from the book published in the Sunday Times, McCann revisits the night of her daughter's abduction from the Portuguese resort of Praia da Luz.

"I ran out into the car park of our holiday apartment, flying from end to end, yelling desperately: 'Madeleine! Madeleine!' It was so cold and so windy. I kept picturing her in her short-sleeved Marks & Spencer Eeyore pyjamas and feeling how chilled she would be.

"Fear was shearing through my body ' Even now, when the dark clouds close in on me, I find myself shaking my head manically and repeating over and over again: 'Not Madeleine, not Madeleine. Please, God, not my Madeleine.'"

The McCanns want the British government to urge the Portuguese authorities to review the case and have written the book to raise money for the Find Madeleine campaign.