A minister has spoken of his disappointment that Fujitsu, the Japanese company behind the Horizon computer system, has not done more for those whose lives were ruined in the Post Office scandal.

After an intensive year of testimony and revelations at the public inquiry, the postal minister, Gareth Thomas, suggested the response of Fujitsu, which earned record profits in the last quarter of the year, had not been strong enough.

Thousands of branch operators were persecuted and even prosecuted over shortfalls in funds caused by the Horizon IT system, which was built by the Tokyo-headquartered firm. Its employees gave evidence in court to secure the convictions of branch operators.

At the start of 2024, Fujistu, which is forecast to have earned more than £1.5bn from the Horizon contract by the time it expires in 2025, apologised for the role it had played.

It has also said it will negotiate a compensation package with the government after the public inquiry led by the former high court judge Sir Wyn Williams has published its report.

Thomas suggested more could have been done since the truth about Horizon emerged. He said: “I’m surprised Fujitsu haven’t done more to indicate remorse. It was a computer system they developed.

“I’m glad they’re still working with the Post Office to make sure the current Horizon system [works], which the Post Office is still having to use while a replacement is in development; I’m grateful to them for the fact that they’re continuing to work with us.

“But clearly there were significant failings, or it would appear, at least, that there were significant failings in the computer system. And we’ll obviously wait for Sir Williams to opine in full on that issue. I think I’m just surprised that they haven’t … wanted to do more.”

A Fujitsu spokesperson said: “We remain committed to providing our full cooperation to the inquiry as Sir Wyn prepares his final report, following the conclusion of the hearings. As we have outlined, we will also be working with UK government on the appropriate actions, including contribution to compensation. We are grateful to all of those involved in the inquiry for their dedication in examining these very complex historical events.”

Earlier this year, the government passed legislation to overturn hundreds of convictions of branch operators, which were based on data from Horizon.

The Post Office expects to have paid out more than £650m in compensation to branch owner-operators by next March, and it has put aside £1bn. Sir Alan Bates, the lead campaigner and subject of the ITV drama Mr Bates v the Post Office, has said he will once again consider taking legal action if all claims are not resolved by next spring. He has rejected government offers over his own case as “cruel” and “derisory”.

Thomas said that under the latest rules, all those who had applied for compensation would by March next year have received 80% of the amount offered even if the total sum was still under dispute.

He said: “There are a series of complex cases still to be sorted, although we have made a lot of progress in just the five months since we’ve been in government. The amount of compensation that’s been paid out has doubled since we came into office.”

The government is looking at the future ownership and structure of the Post Office. The Communication Workers Union has proposed handing it over to branch operators, known as mutualisation. Thomas said he was not convinced this was the best option for an organisation that had a “significant social value”.

He said: “My instinct is that, one of the ways you transform the culture of an organisation like this is to give more power to those who were treated very badly in the past … We’ve got to think through what are the incentives that you build in to the governance of an organisation like the Post Office that really gives postmasters much more of a voice in the key decisions the board of the Post Office has to make going forward.

“Given that the Post Office has got a significant social value in that sense, I don’t think I’m as yet convinced that full mutualisation is the way forward. But how do we ensure postmasters can hold those at the centre more accountable?”