Six Australian women allege they were sexually assaulted by late billionaire Mohamed Al Fayed, with more than 400 people contacting the legal team representing the accusers.
The Egyptian businessman, who died last year at the age of 94, is accused of multiple counts of rape, attempted rape and sexual assault by women who worked for him.
He always denied similar accusations before his death, but a BBC documentary unearthed new allegations last month.
A lawyer for the accusers, Bruce Drummond KC, told the ABC that five of the Australian women who accuse Mr Al Fayed of sexual assault were employed at Harrods, the luxury London department store Mr Al Fayed owned between 1985 and 2010.
He said the other Australian woman was working for a supplier to Harrods. All the women were in their twenties.
"It was the most wonderful thing they had, quite understandably, working for this amazing store, working for this very powerful individual who was a billionaire … then a lot of them, after they had been subjected to this horrific ordeal, fled [back to Australia]," Mr Drummond KC said.
He said the women weren't concerned that Mr Al Fayed wasn't alive to face justice.
"It's about seeing justice in their own eyes and justice for these ladies means accountability, which means that we out him for the monster he was ... it means setting a precedent so young girls in the future don't go through the same thing," he said.
The legal team representing the accusers, the Justice for Harrods Survivors (JFHS), said alleged victims have come forward from the United States, Spain, Malaysia, South Africa, Japan, Denmark, Canada, Australia and the UK.
"That, in our opinion is an industrial scale abuse, abuse that could only have been perpetrated with a system that enabled the abuse to happen," he said.
"This … is the worst case of corporate sexual abuse of women the world has ever known."
He said alleged victims included the daughter of a former US ambassador to Britain and the daughter of a well-known soccer player, without providing their names.
The JFHS legal team was also investigating claims Mr Al Fayed sexually assaulted several children, including an 11-year-old.
"He's a vile monster, there's no other way to describe it," he said.
Legal action against Harrods underway
Dean Armstrong KC, who was leading the JFHS group, said that hundreds of alleged victims and some 20 witnesses had contacted the group with allegations of misconduct.
"The sheer scale of abuse perpetrated by Al Fayed, and facilitated by those around him, sadly, continues to grow," Mr Armstrong KC told a press conference in London.
He said the first statement of claim had been sent to Harrods on Wednesday, local time, officially starting the legal process.
"It will be followed by hundreds more," he said, adding that the group had received a £1 billion ($1.96b) backing from a legal firm to work through the claims.
"If we are pushed, if our survivors are pushed, into having to defend themselves in order to achieve justice, we are ready. We are resourced and we are determined," he said.
Mr Al Fayed was a household name in the UK thanks to his wealth, eccentricity and connection to Princess Diana.
His son Dodi was romantically involved with the Princess, but both were killed in a car crash in Paris in 1997.
'Team of enablers' allowed alleged abuses to occur
Lawyers said there were reports of Mr Al Fayed assaulting women at Fulham Football Club, which he owned for 16 years, along with abuses at his Surrey estate in England, in aircraft, at the Ritz Paris hotel and Harrods department store.
Mr Armstrong indicated on Wednesday that other sporting organisations linked to the alleged abuses would also be named in due course.
He was critical of the response to the scandal from Harrods, Fulham FC and the Al Fayed estate, calling on them all to "do the right thing".
He added he expected the "team of enablers" that allowed the alleged abuses to occur throughout the businessman's network to be named and prosecuted in the future.
Earlier this month, former Fulham Football Club captain Ronnie Gibbons came forward with allegations that she was assaulted twice by Mr Al Fayed.
In a pre-recorded message on Wednesday, she thanked all women who had come forward.
"I know by speaking out we are making it harder for this behaviour to be tolerated anywhere," she said.
A former manager of the Fulham women's team told the BBC last month that that players were not allowed to be left alone with Mr Al Fayed, after members of staff became aware that the late billionaire "liked young, blonde girls".
The club previously said the allegations aired in the BBC documentary were "disturbing".
The new owners of Harrods confirmed earlier this month that they were in talks with some 250 people seeking compensation for the alleged abuse.
Legal teams representing accusers have been critical of the Harrods compensation scheme, with lawyers saying many alleged victims don't feel comfortable returning to the store where the alleged abuse took place.
Store management previously said it was utterly appalled by the allegations.
London's Metropolitan Police said investigations were ongoing into Mr Al Fayed after some 60 people recently came forward with allegations.
JFHS lawyers said other police forces in the UK were investigating other allegations related to Mr Al Fayed.
