Metropolitan Police detectives are looking at “potential fraud offences” committed during the Horizon IT scandal.
More than 700 Post Office branch managers were handed criminal convictions after faulty Fujitsu accounting software made it appear as though money was missing from their outlets.
It has been described as the most widespread miscarriage of justice in UK history and a public inquiry into it is ongoing.
Scotland Yard said on Friday evening that officers are “investigating potential fraud offences arising out of these prosecutions”, for example “monies recovered from sub-postmasters as a result of prosecutions or civil actions”.
The Met has already been looking into potential offences of perjury and perverting the course of justice in relation to investigations and prosecutions carried out by the Post Office.
Two people have been interviewed under caution but nobody has been arrested since the investigation was launched in January 2020.
After ITV aired a drama into the scandal, Mr Bates Vs The Post Office starring actor Toby Jones, 50 new potential victims have approached lawyers, it has been said.
Neil Hudgell, a lawyer acting for claimants, told the BBC the new enquiries include former sub-postmasters who were given convictions.
He said: “The majority of (those 50 new enquiries) were not prosecuted but lost their livelihoods, lost their homes.
“But there’s a small handful of people who were convicted that have come forward, three in total at the moment, which is obviously a tiny number proportionate to those that are still out there.
“And I think the common feature of these is totally unsurprising. It’s people that have been so heavily damaged by [the] Post Office psychologically that they have been so fearful of coming forward and going through the process again.”