NEW YORK (CNN) -- Celebrity photographer Annie Leibovitz could lose the right to her entire portfolio of world-famous photographs if she doesn't meet a Tuesday deadline to pay back a $24 million loan she is alleged to owe.
Annie Leibovitz appears before her photo of Demi Moore during an exhibition of her work in June in Madrid, Spain.
Leibovitz, who has photographed everyone from the Rolling Stones to Queen Elizabeth II, put her art, intellectual property and even real estate assets up for collateral last year when she consolidated her massive debts.
Art Capital Group, which restructured the debts, says Leibovitz agreed "to make Art Capital her 'irrevocable exclusive agent'" of the assets "in exchange for a reduced interest rate on the loan."
Now the company is suing Leibovitz for breach of contract, saying she has "refused to cooperate in the sale of those assets," according to a question-and-answer sheet on the lawsuit issued by Art Capital. It also says she has "refused to pay to Art Capital hundreds of thousands of dollars she owed as part of the same agreement."
Asked by CNN for comment, Leibovitz's attorney, Steven Brawer, said, "I don't have anything I can tell you." They have until October 1 to respond to the lawsuit.
In the question-and-answer sheet, Art Capital says Leibovitz "acknowledged that in order to repay the loan she would sell her fine art, intellectual property and real estate assets. She authorized Art Capital to act as agent in the sale of those assets through which Art Capital could recoup its decrease in interest rate. She would have realized a significant gain from that sale."
It says the loan agreement gave Art Capital "the right to sell the collateral before the loan came due on September 8 and for a two-year period thereafter."
One of Leibovitz's best known photos is of John Lennon with his wife, Yoko Ono, shortly before the Beatles star was assassinated in 1980.
She is no stranger to controversy.
In 1991, Leibovitz photographed a nude and extremely pregnant Demi Moore for the cover of Vanity Fair. The issue, considered scandalous at the time, was sold in many places nationwide with a sheath of white paper.
Last year, Leibovitz photographed Disney star Miley Cyrus wrapped in a bedsheet, eliciting claims that the photographer pressured the teen queen into poses that were too provocative for her young age.
In July, Art Capital filed a complaint with the New York Supreme Court, asking it to uphold the sales agreement it signed with Leibovitz, including its right to sell her art and real estate.
If the court agrees with Art Capital, it means Leibovitz could end up owing far more than she did originally. Art Capital has asked for an unspecified amount of damages in addition to the money it says the photographer originally borrowed.
Art Capital -- through its affiliate, American Photography -- provides financial and consulting services to artists, galleries and art owners, and offers loans based on their intellectual property and fine art assets.