MPs investigating the Horizon scandal are demanding to see a note that a former chair of the Post Office says he sent to record his claim that he was instructed to stall on payments to wrongfully convicted post office operators. The use of powers by parliament’s business and trade committee to see the note comes amid pressure on the business secretary, Kemi Badenoch, to back up claims that the former Post Office chair Henry Staunton was under investigation for bullying when she sacked him. A war of words between Staunton and Badenoch – who launched an extended attack on him in parliament on Monday – erupted over the weekend after he gave an interview to the Sunday Times accusing the government of wanting to stall compensation payments to victims of the Horizon scandal until after the general election. On Monday night, Staunton issued a stinging riposte to Badenoch, saying he had kept a record of the alleged comment from a senior civil servant asking him to stall compensation payments to Horizon victims. A spokesperson for Staunton said he “recorded [it] at the time in a file note, which he emailed to himself and to colleagues and which is therefore traceable on the Post Office server”. A spokesperson for the prime minister, Rishi Sunak, said on Tuesday that Downing Street would encourage the Post Office to share the note referred to by Staunton if it exists so it can be investigated. “If such a note exists, we obviously would encourage the Post Office to share it so it can be investigated and take any action as necessary,” said the spokesperson. Liam Byrne, the chair of parliament’s business and trade committee, has already invited Staunton to appear before its members and said it would now be going a step further. “Today we will be sending for the papers that we need to try and get to the truth. Crucially, we’ll be sending for that file note that Mr Stanton says that he made that sets out that go slow order that he says he received from senior civil servants in the department, but which the secretary of state professed no knowledge of yesterday. “I’m afraid that there is talk in Westminster about whether the department has gone slow in order to put the financial liabilities on the other side of the election, and I very much hope that’s not true. But we have got to get to the bottom of it, the Department for Business and Trade does have a budget that is under strain. So there is potentially an incentive.” Byrne said it could be true that a senior civil servant had told Staunton to go slow and it could also be true that the secretary of state did not wish that to happen. The wider scandal took another turn with a revelation that the government of David Cameron knew that the Post Office had ditched a secret investigation that might have helped wrongly accused post office operators to prove their innocence. Ministers in his government were told that an investigation in 2016 would address suggestions that branch accounts using the flawed Horizon IT system might have been remotely tampered with, the BBC reported after the release of documents under the Freedom of Information Act. Until 2019, the Post Office continued to claim publicly that the accounts could not be accessed remotely. Paul Marshall, a barrister who represented some post office operators, told the BBC that the documents raised fresh questions. “On the face of it, it discloses a conspiracy by the Post Office to pervert the course of justice,” he said. The investigation, ordered in 2015, was stopped when post office operators launched legal action. Sajid Javid, the business secretary in 2015-16, was among those in government who were told that the investigation was under way to “address suggestions that branch accounts might have been remotely altered without complainants’ knowledge”. He has declined to comment while a public inquiry into the Horizon scandal is under way, while the Post Office has said it is for the inquiry to reach conclusions on what occurred. The BBC reported that there was no suggestion in the documents that Cameron, who is now the foreign secretary, knew about the investigation or that it had been ditched.