The Crown Prosecution Service has said it is still considering whether to charge Sun reporter Mazher Mahmood with perjury a year after the collapse of the Tulisa Contostavlos drug-dealing trial.
It has also emerged that seven people prosecuted for criminal offences as a result of stories by former News of the World investigations editor Mahmood are seeking leave to appeal against their convictions.
Lawyers representing the seven, who include former London's Burning actor John Alford and ex-boxer Herbie Hide, are believed to be arguing that there are "serious concerns" over the safety of the convictions, and that the "common thread" to all six cases concerns Mahmood's integrity as a witness.
There are also references to Mahmood's methods, and to his use of journalistic privilege to keep his alleged sources secret.
Alford was given a nine-month jail sentence after having been convicted in 1999 of supplying drugs to Mahmood – he served six weeks after agreeing to be tagged – while Hide was given a 22-month sentence, reduced on appeal to 18 months, in 2013 after admitting conspiring to supply cocaine to Mahmood, who was by then working for the Sun on Sunday.
The seven are being represented by consultant solicitor Siobhain Egan of Lewis Nedas Law.
The bid for permission to appeal follow the collapse in July last year of the trial of singer and former X Factor judge Contostavlos, when Judge Alistair McCreath told the jury at Southward Crown Court that there were "strong grounds" to believe that Mahmood had lied on the witness stand and "had been manipulating the evidence".
Mahmood was the chief prosecution witness in the case against Contostavlos, which was brought after a drugs deal in which she was allegedly involved was exposed in the Sunday on Sunday in June 2013.
The Crown Prosecution Service (CPS) said today it was still considering whether prosecute Mahmood for perjury following the collapse of the trial.
A CPS spokeswoman said today: "Following a ten-month police investigation, the CPS received a full file from the Metropolitan Police Service on Friday June 5 relating to allegations of perjury and conspiracy to pervert the course of justice.
"This is a complex area of law and it is vital that the file is carefully considered. A decision will be made as soon as is practicable."
Since the collapse of the Contostavlos trial, the CPS has withdrawn a number of criminal charges brought as a result of investigations by Mahmood.
In January, it dropped the case against 13 footballers investigated over alleged match-fixing, saying there was "insufficient evidence to provide a realistic prospect of conviction".
In December last year the CPS said it was re-examining 25 cases in which people were convicted and in which evidence was given by Mahmood.
The CPS also said it had offered no evidence in three live cases where the undercover journalist was a prosecution witness.