She started the year leading the chorus of opprobrium against President Donald Trump but 12 months on Meryl Streep, multiple Oscar-winner and doyenne of the liberal Hollywood elite, has become a target herself.

The 68-year-old is coming under fire over her denials that she knew about the misconduct of movie mogul Harvey Weinstein, who is alleged to have spent his career sexually assaulting, harassing and intimidating women.

Streep has worked on several Weinstein produced films and jokingly referred to him as "God" at the 2012 Golden Globes.

The pre-eminent actress of her generation, Streep has had a glittering 40-year career that has seen her play everything from a Nazi concentration camp survivor to an ABBA-singing mother.

She earned her first of a record 20 Oscar nominations in 1979 for the Vietnam war drama "The Deer Hunter" and has won the coveted golden statue three times, most recently in 2012 as Margaret Thatcher in the Weinstein-distributed "The Iron Lady."

It was her political activism rather than her acting prowess that grabbed headlines during the last awards season, as she received widespread praise, and some criticism, for a speech at the Golden Globes denouncing Trump.

All eyes turned to the actress again as the Weinstein controversy broke in early October, when Streep spoke out to say she was "appalled" by the "disgraceful" news and had no idea about the allegations.

Her denials over Weinstein have sparked incredulity, particularly among activists in the #MeToo social media movement against sexual misconduct who have concluded that those closest to the disgraced producer must have turned a blind eye.

- 'Hypocrisy' -

Rose McGowan, one of the campaign's most prominent advocates and an alleged victim of Weinstein, criticized Streep in a since-deleted tweet over plans for actresses to wear black to the Golden Globes in a silent protest against sexual assault.

"YOUR SILENCE is THE problem. You'll accept a fake award breathlessly & affect (sic) no real change. I despise your hypocrisy," McGowan tweeted.

Streep responded in a lengthy statement to the Huffington Post on Monday that she "did not know about Weinstein's crimes, not in the 90s when he attacked (McGowan), or through subsequent decades when he proceeded to attack others."

The new denial has done little to silence her critics, however, and on Tuesday around a dozen posters appeared in Los Angeles, depicting Streep as an enabler of Weinstein, who has always denied nonconsensual sexual contact with any of his accusers.

Sabo, a 49-year-old rightwing guerilla artist and former US marine claimed responsibility for the posters, which show Streep with a red stripe across her face and the text, "She knew."

He added that he had conceived the campaign as retaliation for Streep using her latest film "The Post" to attack Trump, who is facing accusations of his own by as many as 16 women who say he sexually assaulted them.

Entertainment writer Ira Madison III wrote in a commentary for the Daily Beast that Streep's denials rang true, arguing that the rough ride she has had over Weinstein is nothing more than a manifestation of the sexism inherent in show business.

- 'Viciously attacked' -

"Here we are, attacking a woman for what she may or may not have known, when everyone seems to insist that everyone in the industry knew," he said.

"Why then, have George Clooney or Brad Pitt, not been as viciously attacked as Streep? Why not Bob Weinstein, his own brother, who's remained relatively unscathed from Harvey's downfall?"

Beneath the rarified air of the Hollywood Hills, the public seems less willing to give Streep the benefit of the doubt.

Celebrity branding expert Jeetendr Sehdev solicits opinions twice a year about the rich and famous from 2,000 randomly-selected adults across America as part of an ongoing study established in 2012.

He said 58 percent of those surveyed in October on attitudes to the Weinstein controversy "now feel negatively towards the once beloved Streep" following her initial denials.

"Streep's claims that she didn't know are ludicrous and the kiss of death for her image in Hollywood," the bestselling author of The Kim Kardashian Principle told AFP.

He accused Streep of underestimating the intelligence of the public and the courage of female peers who had spoken out against Weinstein, adding that Clooney also had questions to answer over his response to the scandal.

"Streep needs to apologize to her fans for not telling the truth. And perhaps explain what pressures she was feeling to make such a public statement to begin with," Sehdev said.

"Many people assume that Weinstein reaches out to his close friends to see if they could speak out on his behalf and try to damage control. Were Streep and Clooney part of this pact?"