The Post Office is contacting hundreds of people who may have been wrongfully prosecuted after the post office operator miscarriage of justice scandal.

Dozens of post office operators were prosecuted for theft, fraud and false accounting because of the Post Office’s defective Horizon accounting system, which had “bugs, defects and errors” from the outset.

Last month, 39 former post office operators who were convicted and even jailed based on Horizon data had their convictions overturned by the court of appeal.

The court ruled the convictions were unsafe because the Post Office knew there were faults in the Horizon accounting system it used but continued to pursue prosecutions against its employees.

Some of the convicted workers were sent to prison, others lost their livelihoods and their homes. Many went bankrupt – and some died before their names were cleared.

The Post Office said it was contacting about 540 people with potentially relevant convictions and additional information was being sought in another 100 cases.

A spokesperson said: “The Post Office sincerely apologises for serious historical failures. We continue to take determined action for people affected.

“Post Office has made strenuous efforts to identify individuals who were historically convicted and an extensive post-conviction disclosure exercise is taking place to identify and disclose all material which might affect the safety of those convictions.”