Andrew Tate served with legal papers following rape and assault claims

Controversial internet personality Andrew Tate was served with legal papers by UK lawyers Wednesday after Romanian authorities upgraded the severity of the trafficking charge against him and his brother.

Tate, a professional fighter-turned media personality from Chicago who has racked up billions of views online for his rants about male dominance, is being probed over allegations of organized crime, human trafficking and rape. He has denied the allegations.

"This morning, McCue Jury & Partners, lawyers representing the four victims who have come forward so far, delivered a formal letter of claim to him at his premises in Romania," UK law firm, McCue Jury and Partners, said in a press release Wednesday.

According to McCue Jury and Partners, the letter details "the allegations made by the four women, including violent rapes, serious physical assaults and controlling and coercive behaviour."

"The victims have put Tate on notice that depending on his response, legal proceedings will be initiated against him at the High Court in the coming weeks," the press release continued.

The letter was delivered to Tate in person at his address in Bucharest, Romania on Wednesday, where he is under house arrest. This follows new developments in Romanian authorities' investigation into Tate and his brother Tristan on Tuesday.

CNN affiliate, Antena 3, reported Tuesday, citing judicial sources, that Romanian authorities have charged the brothers with human trafficking in continued form, which is a more serious crime than initially charged. Antena 3 also reported, citing prosecutors, that another victim has been added to the case which began initially with six female victims.

After being released from police custody in April, Tate gave an interview to the BBC in early June from the confines of his home. Tate told the BBC's Lucy Williamson that he is "absolutely and utterly sure" that he is innocent of all charges that Romanian authorities have leveled against him which include organized crime, human trafficking, and rape.

Tate, who came to prominence through his online viral commentary geared towards young men, insisted to the BBC that he is teaching young men "to be disciplined, to be diligent, to listen, to train, to work hard, to be exactly like me."