Harvey Weinstein was a "seasoned" sexual predator and rapist who abused his power as a movie-producing titan to prey on vulnerable aspiring actresses, prosecutors said Wednesday as his trial heard from its first witness.

Weinstein, wearing a dark suit, shook his head as New York Assistant District Attorney Meghan Hast painted a picture of a 300-pound (140 kilogram) bully who violently raped, humiliated and manipulated several women, leaving them traumatized for years.

His defense team hit back by saying the fallen film producer engaged in consensual relationships with his accusers, including a "loving one" in which the woman called Weinstein "her casual boyfriend."

That woman, who says Weinstein raped her in a New York hotel room in 2013, was identified for the first time in court as actress Jessica Mann, having until now remained anonymous.

"It will be clear throughout this trial that the defendant knew he was preying on the naive and the defenseless," Hast told the court, saying many of his victims came from broken homes.

"They didn't know they were being lured in on false pretenses. They thought they had got their big break. He was the old lady in the gingerbread house luring the kids."

Defense attorney Damon Cheronis countered that it was "untrue" and "quite the contrary" to call the "Pulp Fiction" producer a predator.

Wednesday's hearing started with Judge James Burke reminding the 12-member jury and six alternates that they must base their verdict on evidence heard in court and not discuss the trial with anyone outside.

Hast then laid out the prosecution's case in a lengthy statement that included graphic descriptions of sexual assaults.

She said Weinstein raped "The Sopranos" actress Annabella Sciorra in the winter of 1993-94 after a pursuit which included him introducing her to the drug valium.

"He left her emotionally and physically destroyed and passed out on the floor," the prosecutor told a packed courtroom with more than 100 journalists in attendance.

Accusers named 
The attorney likewise said Weinstein left former production assistant Mimi Haleyi lying "motionless like a dead fish" after assaulting her in his New York apartment in July 2006.

And Hast accused Weinstein of treating Mann like a "rag doll" after raping her in her hotel room in March 2013.

Before that alleged assault, the court heard, Weinstein injected his penis with erection medication.

Weinstein, 67, faces life in prison if convicted of predatory sexual assault charges related to Haleyi and Mann in the New York proceedings seen as key to the #MeToo movement.

The trial, expected to run until 6 March, will also hear evidence from Sciorra and three other accusers who were named for the first time in court Wednesday.

They are Dawn Dunning, Lauren Young and Tarale Wulff, whose allegations were previously unknown.

Young will allege that Weinstein raped her in 2013. Dunning says Weinstein grabbed her vagina in 2004 and Wulff will testify that the defendant masturbated in front of her.

They will take the stand as the prosecution tries to convince the seven men and five women on the jury that Weinstein engaged in a pattern of predatory sexual behavior.

 Hundreds of emails 
Weinstein's attorney Cheronis said the jurors would see hundreds of emails and other correspondence showing Mann and his client were "in a loving relationship."

A year after the alleged assault, Mann wrote "Miss you big guy!" in one email, and another which said "Thank you for your unfailing support and kindness," Cheronis said.

In February 2017, she wrote to Weinstein: "I love you, I always do. But I hate feeling like a booty call," Cheronis told the court.

"Members of the jury, that is not how you talk about predators, that is not how you talk about your abusers," he said.

Cheronis argued that Weinstein's accusers changed their attitude towards him as the #MeToo movement gathered steam in 2017.

"We will show that the truth has changed since 2013 and the truth can't change. There is only one truth," he said.

Ignited #MeToo movement 
The prosecution's first witness, former Weinstein Company board member Lance Maerov, testified that the defendant regularly bragged about his powerful connections, including to the Clintons.

Weinstein muttered inaudibly as Maerov -- an executive with communications giant WPP -- said the movie mogul's charming public persona was "diametrically opposed" to who he was in private.

"You don't like Mr Weinstein, do you?" said lead defense attorney Donna Rotuno during a brief cross-examination.

"Not particularly," replied Maerov.

More than 80 women have accused Weinstein of sexual misconduct but many of the alleged crimes fall outside the timeframe for bringing charges.

Arriving at court, Weinstein made his way unsteadily up a few steps but without the walking frame he has used for recent proceedings.

The trial continues on Thursday.