The Government has been warned of a potential “second scandal” involving the Post Office after concerns were raised that subpostmasters were convicted over losses involving another IT system.

Labour MP Kevan Jones has called on Post Office boss Nick Read to come before MPs to answer questions after reports about faults with the Capture software used for back office accounting.

Number 10 has said it wants the matter investigated and “robust action” must take place if there are any issues.

The i newspaper first reported concerns about the prospect of a second faulty IT system, following on from the scandal over the Horizon system.

In a letter to Post Office minister Kevin Hollinrake, Mr Jones said: “We know the Capture software was faulty, resulting in corrupted data. We also know that the Post Office knew about these faults at the time, as it openly communicated with sub-postmasters about them.”

A long-time campaigner for subpostmasters, Mr Jones said: “Several former sub-postmasters have now come forward – including some who have spoken openly to the media to put their stories on the record – to say that despite these faults being known, they were accused of being responsible for inaccurate shortfalls.

“Some of these individuals put tens of thousands of pounds of their own money aside to make their accounts balance; many had their contracts with the Post Office terminated, losing their livelihood and their good standing in their community, and some were prosecuted.

We share the concerns. I think we do want this to be investigated

“I am shocked that we are only just beginning to scrape the surface on what seems to be a second scandal involving the persecution and prosecution of sub-postmasters on the basis of evidence from a computer system that was known to be faulty.”

He said that the Business and Trade Committee should ask Mr Read to come before it to take questions about “this potential further miscarriage of justice”.

An ITV drama has put the spotlight on the decades-long Horizon scandal, with the Government earlier this month promising legislation to exonerate subpostmasters amid public anger over the wrongful conviction of hundreds of Post Office branch managers.

The Prime Minister’s official spokesman said: “We share the concerns. I think we do want this to be investigated.

We take very seriously any concerns raised about cases from before the Horizon system was first rolled out in 1999. We are investigating, including specific cases brought to our attention and will transparently publish our findings

“If there are any issues with any other systems we expect robust action to take place. In the first instance the Post Office are looking into these claims because we are aware of a small number of complaints about that system.

“The Department for Business and Trade is actively speaking to the Post Office about their work and scrutinising it and we will consider our approach following that.”

A Post Office spokesperson said: “In 2020, we wrote to all current and former postmasters where we had contact details about the launch of the Horizon Shortfall Scheme.

“More than 25,000 letters were sent and we also advertised the scheme in national newspapers.

“We take very seriously any concerns raised about cases from before the Horizon system was first rolled out in 1999. We are investigating, including specific cases brought to our attention and will transparently publish our findings.”