A woman claims to have realised £7million of her gold is missing nearly two years after the Hatton Garden jewellery raid in the UK.
She said one of her safety deposit boxes was stolen and that she only realised it was missing following the trial of the gang who carried out the raid in April 2015.
The Metropolitan Police is said to be taking the claim seriously - and it would mean the total amount stolen in the extraordinary heist now stands at about £21million ($37 million), the Daily Mail reported.
The allegations reported by Sky News come after seven men were convicted last year over the break-in in London and jailed for between six and seven years.
A Met Police spokesman said: "In June 2016, police received an allegation of theft from a security box relating to the Hatton Garden burglary in April 2015.
"The victim is alleging the loss of a substantial amount of property. The investigation is ongoing."
Before the woman came forward, it was thought valuables worth up to £14 million had been taken. After the trial, two-thirds of the proceeds were unaccounted for.
Dubbed 'Dad's Army' on account of their old age, the gang stole goods from the safety deposit during a meticulously planned break-in over the Easter weekend of that year.
The plot saw the men use a drill to bore a hole into the vault wall before ransacking 73 boxes containing gold, diamonds and sapphires.
While there was much speculation that it was carried out by an elite group of thieves or foreign professionals, it later emerged those responsible were retired hard men.
Last month it was revealed that the gang received more than £600,000 in legal aid - with getaway driver "Billy the Fish" Lincoln, 60, granted the most at £185,449.
A film is being made about the burglary and is set to star EastEnders actor Larry Lamb, who is playing "Guv'nor" Brian Reader, 77, who was jailed for six years.
Reader was the oldest member of the gang which also included Lincoln, Carl Wood, 59, Hugh Doyle, 49, Daniel Jones, 60, Terence Perkins, 67, and John Collins, 75.
The vault and wall will be relocated to the Museum of London so the public can see how it was targeted, although this process is expected to take at least six years.