Mick Jagger has always been one of rock’s bad boys. But in a controversial new biography, author Christopher Andersen claims the 68-year-old rock star had a long-term love affair with a surprising paramour: David Bowie.

The Rolling Stones front man has wooed a long list of beautiful women over the years, including singer Marianne Faithfull, model Carla Bruni and former first lady of Canada, Margaret Trudeau. But Andersen tackles new territory in his book, “Mick: The Wild Life and Mad Genius of Jagger,” revealing a side to Jagger, 68, and Bowie, 65, that may surprise some readers.

The British rock stars first met in 1973, and have remained friends ever since. However, the true nature of their friendship has spawned considerable speculation over the years.

That speculation has now come to an end, according to Andersen, who reportedly interviewed the two stars’ friends and family members for this unauthorized bio.

As Anderson writes, Jagger and Bowie became fascinated with each other as soon as they met and frequently attended one another’s concerts. The stars also, reportedly, sent gifts back and forth as their relationship grew stronger and quickly turned physical.

“Bowie and Jagger were soon spotted everywhere together without their wives,” Andersen writes.

From sitting ringside at the Muhammad Ali-Ken Norton bout to hanging out at the London disco Tramp, these new pals partied across London, according to Andersen.  The rock stars were also caught in some rather intimate moments during their travels. Those instances made onlookers question the true nature of their friendship.

Andersen describes how the rock stars would “cuddle up together” on a hotel room couch. He also writes that Jagger and Bowie made no apologies for these expressions of tenderness.

“Neither superstar complained when one enterprising photographer snapped the two men in a moment of repose, Bowie tenderly cradling Mick’s head in his lap,” Andersen writes.

These details, in themselves, are nothing new. But the book’s most condemning evidence comes from Bowie’s former wife, Angela Barnett.

According to friends and family members interviewed for this book, Bowie’s wife returned to their London home one day to find her husband and Jagger naked and asleep in her bed.

“Angie went upstairs to her bedroom, slowly pushed the door open, and there they were…Both men woke up with a start. ‘Oh, hello,’ said Bowie, clearly taken by surprise. ‘How are you?’”

According to Anderson, Bowie’s wife never lost her cool.

“'I’m fine,” she replied. “Do you want some coffee?”

Barnett later returned with coffee and orange juice for the two men.

The American model and actress never caught Bowie and Jagger having sex. But according to Andersen, Barnett felt certain they had been intimate.

“It was so obvious…I never considered the fact that they hadn’t been screwing,” were Barnett’s words, according to Andersen.

Back-up singer Ava Cherry, who lived in the Bowie residence for a time, also confirmed the true nature of the men’s relationship.

According to Anderson, Cherry allegedly told a friend that Jagger and Bowie “were sexually obsessed with each other” and watched them having sex on many occasions.

Bebe Buell, Steven Tyler’s former flame, also tells Andersen that she had been in bed with Jagger and Bowie and participated in some three-way sex with the stars.

Andersen’s book also reveals some new details about Jagger’s dalliances with women, in particular Angelina Jolie.

The actress appeared in the Rolling Stones’ 1997 music video, “Anybody Seen My Baby.” Jolie was 23 years old at the time, and had just completed the HBO film “Gia,” in which she portrayed the drug addicted supermodel Gia Carangi.

According to Andersen, then-54 Jagger pursued the Hollywood beauty while he was still married to supermodel Jerry Hall.

Andersen also claims that Jolie’s late mother, Marcheline Bertrand, was eager for Jagger to hook up with her daughter, despite the fact that the rock icon was just four years younger than Jolie’s dad, Jon Voight. According to one source in the book, Bertrand believed that Jagger could teach Jolie about fame and how to handle it.