Former Post Office chairman Henry Staunton will face questions from MPs amid a row with Business Secretary Kemi Badenoch over delays to sub-postmaster payouts.
the current Post Office chief executive, Nick Read, and sub-postmasters including Alan Bates will also answer questions put forward by the Business and Trade Committee on Tuesday.
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 sub-postmasters 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 sub-postmasters are still awaiting compensation despite the Government announcing that those who have had convictions quashed are eligible for £600,000 payouts.
Mr Staunton stepped down from the Post Office amid ongoing tensions last month.