Andrew Tate and his brother will stay in custody until 27 February after a Romanian court extended their police detention.
The pair are being investigated over allegations of sexual assault and exploitation.
A judge has decided they must remain in prison for a further 30 days while police investigate.
Tate, a self-proclaimed misogynist, was arrested in Bucharest on 29 December on charges of being part of an organised crime group, human trafficking and rape.
His brother Tristan and two Romanian women were also taken into custody. All deny the charges.
Ramona Bolla, a spokesperson from Romania's anti-organised crime agency DIICOT, said prosecutors requested the second 30-day extension on Thursday to keep all four in detention while investigations continue.
That request was granted on Friday, she said.
A lawyer for the Tate brothers said he considered the ruling "totally unjustified".
"Only an hour ago, the session was closed and the file has 20 volumes," Iona Gliga said.
"I find it very hard to believe that someone has the physical capacity to study the file in such a short time, as only yesterday it reached the tribunal."
A post on Andrew Tate's Twitter account on Thursday said: "I'm in detention as they 'look' for evidence. Evidence they will never find because we are not guilty."
"They have and will continue to ignore and throw away any and all testimony or hard evidence we are innocent," the post said.
"My case isn't about the truth. This is about Politics."
Prosecutors have said the Tate brothers recruited their victims by seducing them and falsely claiming to want a relationship.
Last week authorities in Romania seized several luxury cars from Tate's villa on the outskirts of the capital.
The 36-year-old British-US citizen has 4.4 million followers on Twitter and was previously banned from various prominent social media platforms for expressing misogynistic views and hate speech.
The former Big Brother contestant and kickboxer is believed to have lived in Romania since 2017.