Criminal convictions in 25 cases where evidence was given by "Fake Sheikh" Mazher Mahmood are being re-examined, prosecutors have said.
The Crown Prosecution Service (CPS) said it had also offered no evidence in three live cases where the undercover journalist was a prosecution witness, after reviewing them in the wake of the collapse of the trial of former X-Factor judge Tulisa Contostavlos in July.
Mr Mahmood, probably the most infamous tabloid investigative journalist of his generation, was suspended by The Sun On Sunday after the trial of Ms Contostavlos collapsed.
Last month, his career of going undercover as Arabic royalty to expose wrongdoing by criminals, celebrities and public figures likely ended when Panorama broadcast recent images of him.
He had fought a long legal battle to stop it being broadcast.
Regarding the 25 cases, a CPS spokesman said: "We are now considering past cases which resulted in a conviction in criminal courts in England and Wales based on evidence provided by Mr Mahmood, and have identified 25 cases.
"Over the coming weeks, we will be contacting representatives of the defendants - or defendants themselves as necessary - convicted in these cases in order to provide them with a disclosure pack - details of material which they may consider undermines the conviction in a specific case."
The former N-Dubz star went on trial after allegedly boasting that she could "sort out" cocaine for an undercover Mr Mahmood and put the reporter in touch with her rapper friend Mike GLC - real name Michael Coombs.
But both were cleared after Judge Alistair McCreath said there were "strong grounds" to believe the Fake Sheikh lied in the witness box and "had been manipulating the evidence".
The CPS spokesman said on Tuesday: "Following the halting of the trial of Ms Contostavlos and Mr Coombs, we took steps to identify current and past cases involving Mr Mahmood as a prosecution witness.
"We made it our immediate priority to carefully look into live prosecutions... and any past cases which involved a defendant still in custody.
"There were no concluded cases where a defendant was still in custody, but we identified three live cases. Each case was looked at individually and no evidence was offered as we concluded that there was no longer a realistic prospect of a conviction."
In September, several trials at Southwark Crown Court in London were halted because they relied on evidence from the undercover reporter.
The CPS offered no evidence against Dr Majeed Ridha and pharmacist Murtaza Gulamhusein, who were accused of illegally supplying an abortion drug.
And fixer to the stars Leon "Starino" Anderson and co-defendant Ashley Gordon, 21, had drugs charges dismissed after prosecutors said Mr Mahmood was not reliable.