More than 400 alleged victims or witnesses have come forward to lawyers over allegations of sexual misconduct against former Harrods owner Mohamed Al Fayed.

One lawyer representing the Justice for Harrods Survivors group described it as the worst case of corporate abuse of women the world has ever seen.

The abuse allegedly took place at Fulham FC, the Ritz Hotel Paris, Harrods, as well as other places owned by Al Fayed.

Harrods’ new owners have previously said they were “utterly appalled” by the allegations and were investigating whether any current staff were involved.

Al Fayed, who died last year aged 94, was accused by more than 20 women of sexual assault in a BBC documentary and podcast in September.

Since then, more women have come forward with allegations of assault, harassment and rape over a period of more than thirty years when they were his employees.

Harrods previously told the BBC that it was in the process of settling more than 250 claims for compensation brought by victims of Al Fayed. The luxury department store has a compensation scheme for ex-employees who say they were attacked by Al Fayed, which is separate from the legal case against it.

On Thursday, the Justice for Harrods Survivors group, who represent some of the accusers of the former Harrods boss, said its first letter of claim had been sent to the department store, calling it the “beginning of the formal legal process”.

The group said that most of the 421 claims were connected to Harrods, but others related to incidents at Fulham FC and the Ritz Paris hotel, which Al Fayed also owned at the time of the alleged attacks.

The survivors involved come from the UK, America, Canada, Europe, Australia and Asia, the lawyers said.

At the press conference in central London, a video was shown of former Fulham women’s captain Ronnie Gibbons.

Gibbons has previously said she was abused by Al Fayed at an event held at Harrods.

“The truth will set us free,” she said, thanking the other survivors for speaking out.

A number of survivors attended the press conference. Lawyers for some of the victims said that they were working on a claim against the Al Fayed estate, as well as Harrods.

They said they expected to send hundreds more claims to the department store in the coming weeks and that it would “snowball and snowball”.

Dean Armstrong KC, one of the Justice for Harrods Survivors group’s legal team, said: “We are delighted to announce that we have reached an agreement with a major law firm who will be handling the processing of these claims.

“The law firm have areas of expertise in this field and, lest anyone be concerned about our ability to fight this cause to the end, backing of over £1 billion.”

Mr Armstrong called on Harrods, the Al Fayed estate and Fulham FC to “do the right thing”.