The complaint said this police failure reflects an “apathy towards victims” or an “institutional desire to insulate Mr Al Fayed from prosecution”.
The has contacted Al Fayed’s estate for comment.
Ms Spong is being represented by the high profile US lawyer, Sigrid McCawley who led legal actions against Jeffrey Epstein – who died in a New York prison cell as he awaited trial on sex trafficking charges.
“This has gone on too long,” Ms McCawley said. “Too many survivors were victims of Fayed and they reported to police.
“They got zero protection. That’s appalling and it has to stop.”
Ms Spong applied for a job as a PA to Al Fayed in 2008, while living in Paris, aged 23.
She told police later that while in London for interviews, Al Fayed grabbed and kissed her, making clear that sex with the boss was a requirement of the role.
The company also required her to have an intimate medical examination, the results of which, she says, were passed to Al Fayed, who appeared to know she had been diagnosed with a minor infection.
She described what had happened in emails shortly afterwards, to friends and a recruitment consultant, but was too scared of Al Fayed’s power to report him.
Ms Spong finally felt able to come forward nine years later and a Metropolitan Police investigation began.
In June 2018 she was emailed by a detective to say they had been provided with expert evidence about Al Fayed, which would “have an impact” on the investigation.
Thirteen days later a more senior officer said the case would be closed, partly because police had been unable to obtain the businessman’s response to the allegations, due to his health.
The Met said the case couldn’t be referred to prosecutors because there wasn’t enough evidence.
Ms Spong’s complaint to the Independent Office for Police Conduct (IOPC) concludes the decision to terminate the investigation was “premature and flawed”.
The complaint said: “The police… ought to have been more thorough in assessing the substance and veracity” of the medical evidence provided by Al Fayed.
