A man posing as a charity worker was suspected of planning to abduct Madeleine McCann hours before the 3-year-old disappeared in 2007, a new book claims.

A mysterious intruder fled when he was caught in a villa close to the resort apartment in Praia da Luz, Portugal, where Madeleine’s family was staying.

The new book, “Looking for Madeleine” -- by Anthony Summers and Robynn Swan -- focuses on the investigation into the girl’s disappearance. Summers told Sky News that a British mother answered her door to a stranger asking for donations for an orphanage back in 2007.

The woman soon realized the man was staring intently at her young daughter, who was standing at her side. "She later saw that man watching her place during the afternoon. The next day she went upstairs to fetch something for a moment and as she started to come downstairs she saw what she thinks was the same man in the room where her child was and as soon as she started to come into the room he (fled)."

The woman was convinced the man planned to kidnap her daughter, she told Scotland Yard detectives in an interview on the case, Summers said.

The book also reveals how another intruder got into the bed of a young girl in the nearby resort of Carvoeiro three years earlier.

The man chased after the girl and her sister woke up and asked if he was their daddy or uncle, Swan told Sky. "What they noticed about this man was that he was wearing what seemed to be a surgical mask and he had wound laundry around his feet, seemingly to keep from making prints or leaving marks,” Swann said.

"He disappeared without interfering with the two girls."

The authors claim that the McCanns' vacation apartment was being watched in the days leading up to Madeleine's disappearance.

"Two separate witnesses apparently saw a man, whom both described as very ugly or with a spotty or pimply face, staring fixedly at apartment 5A. They both described him being in the same position in the street,” Swan said.

"That's combined with the fact that on the very day Madeleine disappeared, a lady visiting the apartment upstairs saw from her balcony a man behaving very oddly in the lane between the apartments and the pool. The man was going out of an adjacent gate, closing the gate repeatedly to see if it was creaky. He seemed to be looking around and generally acting very peculiarly before leaving," Swan added.

Madeleine was nearly 4 when she vanished. She was sleeping in a room with her younger sister and brother in the apartment while her parents dined with friends in the resort’s poolside tapas bar nearby.

The McCanns said they had left the sliding patio door unlocked, while checking on the children every 30 minutes.

Madeleine’s mother, Kate McCann, has said she was told by then-British consul Bill Henderson that before Madeleine vanished he was aware of a spate of child sex assaults along the Algarve coast and had discussed it with vacation companies, the authors said.

"Had there been a warning note in the apartment, do we think the McCanns would have left the patio door unlocked on the night they went to the other side of the pool to have dinner away from their children? One would be tempted to think they would make sure everything was firmly locked up," Summers said.

A sexual predator and three burglary suspects are the focus of the current Scotland Yard investigation.

Although they did not interview McCann’s parents, Kate and Gerry McCann, the authors spent two years researching Portuguese police files and British documents to write what they claim is the first objective book on the McCann case. The book will be released next week.