In a video update sent to victims, Scotland Yard said women and men had reported crimes, and a number of new witnesses had also contacted the force to give evidence.
The Met is currently conducting an investigation into how it handled historical allegations, including sexual assault and rape, perpetrated by Al Fayed - who died in 2023 aged 94.
It is also looking into whether there may have been others who could face charges for enabling or assisting his behaviour. The force has previously said it was investigating at least five people.
In the update, Detective Inspector Karen Khan said the Met was working with international agencies, including foreign police forces.
She said it was "difficult" to say when the investigation might be concluded because of the sheer number of survivors who had come forward.
She also asked for victims and witnesses to continue to come forward but acknowledged there was a "reluctance" to trust the police by some.
In a further update on Wednesday, the Met said the way the force "works has moved on immeasurably, and our teams have transformed the way we investigate rape and sexual offences".
"We're working with partners across the criminal justice system to ensure that victim-survivors are at the heart of our response, with a greater focus on suspects and their offending," a spokesperson added.
The latest figure of 146 is more than double the 61 people who the Met said had reported allegations the last time it released a number in October.
Harrods said more than 100 victims of Al Fayed's abuse had entered its compensation scheme in July. Al Fayed owned the luxury department store between 1985 and 2010.
The store started issuing compensation at the end of April and the scheme remains open for new applications until 31 March 2026.
Eligible applicants could receive up to £385,000 in compensation, plus treatment costs, if they agree to be assessed by a consultant psychiatrist, or up to £150,000 without a medical assessment, Harrods said in March.
They are also offered a meeting with a senior Harrods' representative to receive an apology in person or by video, as well as a written apology.
The extent of Al Fayed's predatory behaviour was brought to light by a BBC documentary and podcast, broadcast in September 2024.
Al Fayed: Predator at Harrods heard testimony from more than 20 female ex-Harrods employees who said Al Fayed sexually assaulted or raped them.
Since then, dozens more women have come forward with similar experiences.
Responding to the BBC investigation at the time, Harrods' current owners said they were "utterly appalled" by the allegations and that his victims had been failed - for which the store sincerely apologised.
It was only after the broadcast that the Met revealed it had been approached by 21 women before Al Fayed's death, who accused him of sexual offences including rape, sexual assault and trafficking. Despite this, he was never charged with any offences.
In October, the Met said 40 new allegations including sexual assault and rape had been made against Al Fayed, covering a period between 1979 and 2013. These allegations were in addition to the 21 it had already received.
Two complaints against the Met Police for its handing of allegations against Al Fayed are being investigated by the force under the direction of the Independent Office for Police Conduct.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.
PA Media Lawyers representing the Harrods Survivors group speak at a press conferencePA Media One of the lawyers described it as the worst case of corporate abuse of women the world has ever seen
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".
