Lady Gaga is calling BS on Kesha's lawyer, who claims Gaga has accused Dr. Luke of raping her.

Gaga insinuated on Howard Stern Tuesday morning she had been sexually assaulted by a record producer years ago, but she didn't name names.

Mark Geragos just tweeted, "Guess who the rapist was?" Someone responded and asked if it was Luke, and Geragos replied, "#bingo."

Gaga's rep tells TMZ, "It's absolutely not true," although she would not comment on who Gaga was referring to when she made her comment on Stern.

Luke's rep tells TMZ, "Mark Geragos' statement is completely false and defamatory. Luke met Lady Gaga twice for less than half an hour total in those two meetings combined." The rep adds, "He has never been alone with her and never touched her. Neither meeting was in that time frame reported."

But Geragos tells TMZ, "I said it because it's true." Geragos says the Cosby scandal is a trigger for the revelation, saying, "The Cosby allegations have now made others more courageous about coming out."

Geragos says he will depose Gaga in Kesha's sexual assault lawsuit against Dr. Luke. He also tells us 3 other women -- "not as famous" -- also claim they had a similar experience to Kesha's and they will be deposed as well.

Gaga's rep just expanded on the singer's denial, saying, "The Dr. Luke lawsuit is utterly incomprehensible. This simply isn't true and how dare someone take advantage of such a sensitive matter."