A new Diddy accuser claims he was sexually assaulted, raped and humiliated at a "freak-off" party in Miami ... and he says Jay-Z, Beyoncé, LeBron James and Gloria Estefan saw him in rough shape.

Diddy is being sued for human trafficking by a Florida man named Joseph Manzaro, who claims Diddy humiliated him at an April 2015 birthday party for King Combs by strapping a penis to his face and parading him around.

In the lawsuit, obtained by TMZ, Manzaro claims he was drugged and transported to Star Island in Miami for the big party in April 2015 ... he says he was first dragged into the back entrance of Emilio and Gloria Estefan's mansion, where a panicked Gloria saw his "drug-induced stupor" and demanded someone call an ambulance.

Manzaro claims Emilio quickly silenced Gloria and ushered her away into the crowd ... and then he says he saw LeBron walking through a hallway in a bath towel. He says LBJ looked at him and said, "Y'all better do something about that!"

In the docs, Manzaro claims ex-porn star Adria English then led him through a secret tunnel to Diddy's mansion ... and he regained partial consciousness in a large party area, where he noticed Beyoncé and Jay-Z.

Manzaro claims when Beyoncé saw him, she asked ... "What’s this? What's this all about? Why is this half-naked white man with a cock mask standing here in front of me?" He says one of Diddy's goons told Beyoncé, "Diddy wants him to see what we do to snitches. This is part of his punishment."

Diddy's accuser claims he was then forcibly paraded through multiple rooms filled with people who jeered and taunted him ... and he says Diddy ordered him to be degraded, calling out ... "He's gonna find out what we do to snitches tonight. Get him undressed!"

Manzaro says he was stripped and then dressed in a small thong bikini bottom and a black leather mask with a rubber dam forcibly inserted and zipped closed over his head. He says a locking sex device was affixed to the mask, protruding from his mouth ... with Diddy and Adria allegedly subjecting him to degrading and non-consensual acts.

He says later in the night he came across celebrity jeweler Jacob Arabo, who he says was visibly disturbed by his attire. He claims Jacob asked, "What's this? What’s going on with this guy? Why is he standing here staring at me with a penis strapped to his face?"

Manzaro claims Emilio again intervened and told Diddy's goons to get him out of Jacob's sight ... and then Gloria again pleaded for an ambulance, with Emilio silencing her and shoving her away into a crowd.

Jay-Z, Beyoncé, LeBron, Gloria and Jacob are NOT being sued,

Now, it is true Diddy threw a 17th birthday party for his son back in April 2015 -- and while Manzaro is referring to it as a "freak-off" ... the alleged event he describes does not match what prosecutors have said in the federal indictment. They allege the "freak-offs" involved Diddy, a male sex worker and another woman.

BTW ... one quick hole we found in Manzaro's story, with a simple Google search, is that Jay-Z was in NYC on April 1, 2015 -- the date of King's 17th birthday -- for a speaking engagement about Tidal streaming service, which he had just purchased.

Manzaro is going after Diddy, Emilio, Adria and Diddy's alleged drug mule Brendan Paul, among others ... he's suing them for human trafficking and he's seeking damages.

Sean Combs' legal team tells TMZ ... “This complaint demonstrates the depraved lengths plaintiffs will travel to garner headlines in pursuit of a payday. No sane person reading this complaint could credit this story. Mr. Combs looks forward to having his day in court where these lies – and the perverse motives of those who told them – will be revealed.”