Police are investigating “dozens” of people at the Post Office and Fujitsu over the Horizon scandal, a senior police officer has said.
Met Commander Stephen Clayman said investigators had identified "dozens" of people of interest over the scandal, which saw hundreds of sub-postmasters wrongly convicted for theft and fraud due to the faulty Horizon software.
However, no charging decisions have been made until a public inquiry into the scandal publishes its final report.
One hundred police officers from across the UK are now working on the investigation, which is focusing on potential crimes of perjury and perverting the court of justice.
Police have said the inquiry is "unprecedented" in size, with potentially more than 3,000 victims and evidence currently including more than 1.5 million documents that have to be reviewed.
Commander Clayman said: "The scale of the task ahead is unprecedented and I am confident we have an excellent team in place, with the support of cutting-edge technology to strengthen our search for information and evidence in amongst the 1.5 million-plus documents obtained and which will grow.
"I do know that if you take into account Post Office criminal and private prosecutions, civil claims and contract withdrawals, there are potentially thousands of victims who we are working hard to identify and build our database so that we can ensure we reach as many affected individuals as possible.
"I cannot make promises that this will be a fast process. An investigation of this size must continue to be undertaken meticulously and methodically and will take time.
"However, I speak on behalf of our whole team when I say we will approach it with independence, precision and integrity."
Closing statements will be heard in the inquiry on December 16 and 17, but no firm timetable has yet been set for its final report.
This means any potential trials may not take place until 2027.
Last month the Met said four suspects had so far been identified in the investigation, and that the number was expected to rise.
Three have been interviewed under caution so far since 2021, with the most recent in September this year, and more are expected to be questioned next year.
Investigators are looking at "a significant number of people" from the Post Office, Fujitsu and in the legal profession, police said in a briefing for journalists on Tuesday.
More than 900 sub postmasters were prosecuted between 1999 and 2015 after faulty Horizon accounting software made it look as though money was missing from their accounts.
Hundreds are still awaiting compensation despite the previous government saying that those who have had convictions quashed are eligible for £600,000 payouts.
The scandal is one of the most widespread miscarriages of justice in British legal history.
A Post Office spokesperson said: "Post Office has co-operated fully and openly with the Metropolitan Police since early 2020 to provide whatever information it needs for its investigations.
"This has included wide-ranging requests for large volumes of data, all of which we have agreed to. This is in addition to disclosing almost 500,000 documents to the Horizon IT Inquiry.
“We will continue to co-operate with the Metropolitan Police as they undertake their investigations."
