Heather Mills in the 1988 book Freuden der Liebe (Joys of Love). (WENN/NewsCom)

It's been a hard couple of nights for Heather Mills, but Paul McCartney's estranged wife is frantically denying she ever worked like a dog.

U.K. paper News of the World alleges Mills hid a sordid past from her husband that included working as a $10,000-a-night prostitute and engaging in lesbian and group sex with wealthy Arabs.

Mills, 38, garnered headlines in another U.K. newspaper, The Sun, just last week after the paper published steamy photos of the former model engaging in explicit sex acts.

The photos are from the 1988 book Freuden der Liebe (Joys of Love), available to order from orion.de, a German website selling sexual material.

Though the paper called the photos "obscene and pornographic," Mills explained that pictures of her posing intimately with a curly-haired male model were meant to be an instructional "lover's guide."

As for allegations she was a high-class prostitute, lawyers issued a statement over the weekend trying feverishly to refute the shocking stories, saying "the sources clearly are a variety of unreliable persons who have been paid."

"The timing of the article is clearly designed to cause maximum hurt to Heather, her husband and family at this sensitive time," the statement read.

News of the World devoted a four-page spread to the explosive story on Sunday, claiming they obtained sworn affidavits from the private secretary who paid Mills for "pleasuring his billionaire master" -- an international arms dealer.

In a detailed interview with the secretary, the paper reveals lewd details of her sexual exploits that spanned Spain's poshest resort towns and London hotels.

"She has lied through her teeth," the secretary said in response to her denials.

High-profile ex-prostitutes also corroborate claims Mills was a sought-after escort while in her 20s.

One woman described how she and Mills -- who she said wore stockings and stilettos for the romp -- engaged in a foursome with a Saudi prince. Each woman earned about $2,000.

"The prince was really excited, especially when Heather performed a sex act on me. Then he had unprotected sex with her," the woman told The Sun.

Another former prostitute who claims she too was intimate with Mills said, "Heather was a familiar face in our business."

"I worked with her when we were both hired for a party thrown by an Arab prince...," she said, adding that Mills "was bubbling over with enthusiasm."

According to Mills' lawyer, the tabloid that broke the story held on to the allegations for four years under threat of legal action from McCartney's lawyers.

But Mills is no longer under his protection since the couple, who have a 2-year-old daughter, announced last month they were filing for divorce.