Australian movie star Rebel Wilson has launched a vitriolic Twitter tirade at a journalist who allegedly “harassed” her sick grandmother.

The problem was, she accidentally and publicly attacked an innocent and unsuspecting victim in full view of her 2.43 million followers first.

On Friday, the Hollywood actress wrongly accused a journalist from House and Garden magazine of pursuing her elderly grandmother.

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The overzealous naming and shaming of the “disgraceful and upsetting” journalist – who she claimed had been targeting her grandmother – failed when Wilson tweeted a photo of the person she thought to be the perpetrator.

“Here she is: total scum,” she posted on Friday, along with a photo of the reporter she believed responsible.

“If your name is Elizabeth Wilson and you work for ACP Magazines, just know that you are a disgrace for harassing my sweet, sick grandma,” Wilson then tweeted.

After Wilson sent the “scum” tweet, it soon became clear that she had been making accusations against an innocent reporter.

Photo:Twitter

Photo: Twitter

Photo: Twitter

Wilson deleted the original tweet, which was accompanied by a photo of the wrong reporter and apologised for her mistake.

But her inaccuracy had already infuriated many.

“Free advice from a fan. The longer you leave the pic of wrong woman up titled ‘total scum’ the more it’s likely to cost you,” Peter Ford tweeted.

Meanwhile @AP_TLD posted: “Was a HUGE fan but now I’ve lost all respect for you. I feel bad for your nan. But you can’t do this to innocent Liz.”

The wrongly accused Elizabeth Wilson works for Bauer Media-owned Home and Garden magazine. German firm Bauer Media bought ACP magazines in 2012.

The New Daily contacted Rebel Wilson’s management, House and Garden magazine and Elizabeth Wilson for comment.

Rebel lambasts another Elizabeth Wilson

After ignoring the issue on Saturday, Rebel Wilson returned to Twitter on Sunday to berate another reporter with the name Elizabeth “Lizzie” Wilson.

Photo: Twitter

Photo: Twitter

These tweets were followed by more attacks on the journalist who she believed was “confirmed” as responsible.

“This Elizabeth Wilson, it is now confirmed, was the one who harassed my 86 year old frail grandma,” Rebel Wilson alleged.

“Her actions are so disgraceful and upsetting and she should be shamed for this conduct. Authorities have been contacted.

The journalist has denied Rebel Wilson’s claims. Photo: Getty

“I was only trying to protect my beautiful grandma who is the kindest, loveliest person from harassment and verbal abuse.”

The actress did not expand on what exactly Elizabeth Wilson allegedly did to her grandmother.

Speaking to Mamamia, Elizabeth “Lizzie” Wilson denied the allegations made by Rebel Wilson on Twitter.

“I am fiercely rejecting the allegations that have been made against me regarding the harassment of Rebel Wilson’s grandmother. I have never, ever, harassed anybody, let alone an elderly person,” Lizzie Wilson said.

“These claims are so abhorrent.”

The reporter went onto explain she was commissioned to write the piece by a “reputable” magazine as she was working as a freelancer, and was not employed by a Bauer magazine.

Tumultuous year for Rebel Wilson

While Rebel Wilson’s on-screen fortunes continued to grow in the past 12 months – with roles in Hollywood films Pitch Perfect 2, How To Be Single and Grimsby – she has endured a torrid time off it.

In May, she came under scrutiny from women’s news website Mamamia, which alleged she had been lying about her age.

The latest attack has reminded some of other incidents. Photo: AAP

Only two weeks ago, she was pilloried for a speech some deemed “racist” at the BAFTA Awards in the United Kingdom.

While addressing black best supporting actor nominee Idris Elba, Wilson played the ‘flustered girl with a crush’ card she is well-known for.

“Sorry, Idris Elba … You’re making me a bit nervous,” she said. “But I’m just psychologically programmed to want chocolate on Valentine’s Day.”

Then, noting that she’d love to return to the BAFTAs to receive an award one day, Wilson said: “I’ve been practising my transgender face.”

The joke appeared to poke fun at both Eddie Redmayne’s nominated portrayal of a transgender person in the acclaimed film The Danish Girl, and the supposed easy awards that come with playing a trans person on screen.

Both jokes were received awkwardly at the awards and then with scorn on Twitter and in the media.