Post Office lawyers threatened BBC journalists over Horizon programme
Panorama looked into the Horizon IT scandal in 2015
The Post Office threatened and lied to the BBC in 2015 before a Panorama programme with a Horizon whistleblower, the public broadcaster said.
The BBC said experts who were interviewed for the programme were sent intimidating letters by Post Office lawyers who also sent letters to the broadcaster, threatening to sue Panorama.
According to the BBC, senior Post Office managers also told the broadcaster at the time that no staff or the company who developed Horizon, Fujitsu, could access subpostmasters accounts, despite being warned four years earlier this was possible.
The BBC says the claims did not stop the programme, titled Trouble at the Post Office, but it did delay the broadcast of the show.
The Post Office has been contacted for comment. It told the BBC it will not comment while the public inquiry continues.
The Horizon scandal saw more than 700 subpostmasters and subpostmistresses handed criminal convictions after faulty Fujitsu accounting software made it appear as though money was missing at their branches.
Victims have described being shunned by their communities, financially ruined and having their families destroyed.
The Post Office public inquiry into the scandal will continue in London today (Friday.)
Chief Executives of Post Office and Fujitsu are set to be questioned by MPs over the Horizon scandal next week.