Sir Ed Davey has accused Post Office bosses of unleashing a “conspiracy of lies” as he mounted a defence of his role in the Horizon IT scandal.
The Liberal Democrat leader, who was postal affairs minister from 2010 to 2012, has been accused of “fobbing off” victims of the scandal.
And former Post Office branch managers, hundreds of whom were given criminal convictions after faulty Horizon accounting software, developed by Fujitsu, made it appear money was missing.
Ex-postmasters have urged Sir Ed to “look in the mirror” and consider stepping down.
But, in an interview with The Guardian, Sir Ed lashed out at “the people in the Post Office who were perpetrating this conspiracy of lies”.
He said it is important to “get to the truth” and that “they are held to account”.
Liberal Democrat sources have told The Independent that Sir Ed is being scapegoated in a general election year, in a bid to damage Lib Dem hopes in the Tory blue wall.
And Lord Arbuthnot, a former MP who sits on the Horizon Compensation Advisory Board and campaigned for the postmasters when he was an MP, told Sky News the focus on Sir Ed was “a bit of a red herring”.
Addressing his time as postal affairs minister, Sir Ed said: “We were reassured time and again that the Horizon system was working. We were told there weren’t that many postmasters affected. We were just told so many lies,” he said.
“We absolutely have to have these people completely exonerated – their convictions must be overturned. The Post Office lied to judges and the courts.”
But the newspaper said he refused to apologise for his role in the scandal as he issued a personal defence.
Sir Ed went on to question why the Conservatives had awarded former Post Office boss Paula Vennells a CBE, amid mounting pressure to rescind the gong. A petition calling for her to be stripped of the honour has gathered more than a million signatures.
“They knew all about this,” he said. “I’d like to know who signed it off. It was a bizarre decision given that this was clearly in the public domain.”
The Tories have been attacking Sir Ed over the scandal, with Conservatives fearing a threat posed by the Lib Dems at the next general election.
Tory deputy chairman Lee Anderson accused him of having taken “the side of the employers over the workers”.
“This man, this Ed Davey, has not really looked at both sides of the story. He took the side of the Post Office employers and sadly many went to prison due to him not listening,” Mr Anderson told GB News, which employs him as a presenter.
“But he really should be coming out now - instead of making excuses, instead of saying he was lied to, he should properly apologise, make a public apology in Parliament to these people that sadly took their lives, the families of these victims, and the people who went to prison.”
The renewed focus on the scandal comes amid a new ITV drama, Mr Bates vs the Post Office.
Alan Bates, played by Toby Jones, has spent two decades of his life fighting for justice after hundreds of fellow postmasters and postmistresses were accused of theft, fraud, and false accounting due to faulty computers.
In 1999, Horizon, a defective Fujitsu IT system, began incorrectly reporting cash shortfalls at branches across the country. The accusations tore people’s lives apart, with many losing their jobs and homes.
Several people took their own lives due to the stress.
To this day, not a single Post Office or Fujitsu employee has been held to account over the scandal, much less faced criminal investigation. Sixty of the victims have died before finding any justice at all.