Weinstein allegedly raped a woman at a hotel after pushing his way inside her room, Los Angeles District Attorney Jackie Lacey said in a statement. The next day, he sexually assaulted a woman at a hotel suite in Beverly Hills, the statement added.
"We believe the evidence will show that the defendant used his power and influence to gain access to his victims and then commit violent crimes against them," Lacey said.
Lacey later told reporters that the complaints were filed in 2017.
"It is very challenging to get those victims to open up and tell us what they needed to tell us, for some it was embarrassing, it was terrifying," Lacey said.
Lacey said the announcement was not tied to Weinstein's trial in New York, adding three more cases in which Los Angeles prosecutors are still deciding whether to press charges in three other cases involving the producer.
Across the country, Weinstein appeared in a Manhattan court for a trial that's set to be closely followed around the world as the highest-profile #MeToo case to go before a criminal court jury.
In New York, Weinstein faces five charges stemming from allegations that he raped a woman in 2013 and performed a forcible sex act on another in 2006. The two accusers are set to take the stand, with a third woman expected to testify that Weinstein raped her in 1993.
If convicted of predatory sexual assault, he could face life in prison.
The 67-year-old arrived at New York State Supreme Court with dishevelled hair, wearing a black suit and tie and accompanied by lawyers. He entered the building with the aid of a walking frame, as he did at court appearances in December. The move prompted speculation that he was attempting to garner sympathy.
A number of Weinstein's female accusers, among them the actresses Rosanna Arquette and Rose McGowan, waited for him in front of the court building.
Once Weinstein and his legal team arrived in the courtroom, Judge James Burke called the court session to order. The prosecution and defence then began to debate what evidence to allow under a new New York discovery law.
Prosecutor Joan Illuzzi described Weinstein as a "predator" and accused lead defence attorney Donna Rotunno of "degrading and humiliating" witnesses in prior media appearances.
The judge refused to bar either side from speaking to the press but warned them to "leave the witnesses alone," saying it would be difficult enough to find a fair jury.
Jury selection for Weinstein's trial is set to begin on Tuesday.
The high level of public interest in the case means that selecting impartial jurors could take anywhere from several days to several weeks.
The judge denied a motion to sequester the jury during the trial - request made by the defence to prevent jurors from being influenced by media coverage.
More than two years have passed since US news outlets detailed numerous allegations against Weinstein, leading other alleged victims of sexual assault to come forward as part of the #MeToo movement.
"People are going to be looking to this case to see if there is going to be accountability in a court of law against a rich, powerful, famous person who's been accused by so many women of sexual assault," Gloria Allred, the attorney for several accusers who are expected to take the stand, told reporters.
Weinstein, who was arrested in May 2018, has pleaded not guilty to all charges and has been free on bail.
More than 80 women, including Gwyneth Paltrow and Angelina Jolie, have accused Weinstein of sexual misconduct. He has denied all allegations of non-consensual sex.
In December, Weinstein and his former film studio reached a tentative 25-million-dollar settlement with 30 accusers, US media reported. The deal would end nearly all civil lawsuits against Weinstein, who would not have to admit any wrongdoing or pay anything out of his own pocket.
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