Former Post Office chairman Henry Staunton is to be brought before MPs to give evidence next week amid an increasingly bitter row with Business Secretary Kemi Badenoch.
The Business and Trade Committee said that current Post Office chief executive Nick Read and subpostmasters including Alan Bates will also answer questions on Tuesday February 27.
The parliamentary select committee said the witnesses will update MPs on progress on redress to victims of the Post Office Horizon scandal.
The Horizon IT scandal saw more than 700 subpostmasters and subpostmistresses handed criminal convictions between 1999 and 2015 as Fujitsu’s faulty Horizon system made it appear as though money was missing at their branches.
Hundreds of subpostmasters and subpostmistresses are still awaiting compensation despite the Government announcing that those who have had convictions quashed are eligible for £600,000 payouts.
Mr Staunton, who will answer questions on Tuesday afternoon, stepped down from the Post Office amid ongoing tensions last month.
The former WH Smith executive has since been involved in a deepening row with Ms Badenoch after he claimed he had been told to delay payouts to postmasters affected.
Ms Badenoch hit back on Monday by telling MPs he had spread “made-up anecdotes” following his dismissal.
However, on Tuesday morning, ministers faced fresh pressure after allegations a senior civil servant told Mr Staunton not to focus on “long-term issues” and to protect his organisation’s finances.
Mr Staunton is said to have been told during a meeting with Sarah Munby, who was then permanent secretary at the Department for Business, Energy and Industrial Strategy (BEIS), to “hobble” into the next general election, according to notes reported by the Times.
Next week, MPs will also hear from legal representatives from the Department of Business and Trade administering the group litigation order (GLO) scheme designed to compensate 555 subpostmasters, and lawyers for claimants of this and all other schemes, the Commons said.