The Sun is facing a fresh crisis after one of its most colourful and scoop-generating journalists was suspended by the paper, after being accused of telling "lies" that led to the collapse of the trial of Tulisa Constostavlos.
SEE ALSO: Tulisa's Drugs Trial Collapses
Constostavlos condemned undercover reporter Mazher Mahmood, known as the Fake Sheikh, for "openly lying" to the judge and jury in her trial for allegedly brokering a drugs deal, which was brought about by one of his notorious stings.
She said she was the victim of a "disgusting entrapment".
Mahmood, who is famous for his exposing unwitting celebrities and used to work for The News Of The World (NoTW), posed as a wealthy film producer to meet Constostavlos and allegedly broker a drug deal, which he then reported on the front page of The Sun On Sunday last June.
But the trial was stopped after the judge said there were "strong grounds to believe" Mahmood had lied at an earlier hearing in the case.
It is bound to be another headache for News UK, the re-branded News International that owns The Sun and its now-closed stablemate NoTW, which has only just emerged from the fallout of the phone hacking scandal and trial.
That scandal saw former NoTW editor Andy Coulson go to prison and former News International chief executive Rebekah Brooks acquitted.
After Constostavlos's drugs trial collapsed earlier today, The Sun said he had been suspended while it investigated.
A spokesman for the paper said: "We are very disappointed with this outcome, but do believe the original investigation was conducted within the bounds of the law and the industry's code.
"This was demonstrated by the decision to prosecute.
"The Sun, of course, takes the judge's remarks very seriously. Mr Mahmood has been suspended pending an immediate internal investigation."
Standing on the steps of London's Southwark Crown Court after the trial stopped, Tulisa said: "This whole case was a horrific and disgusting entrapment by Mazher Mahmood and The Sun on Sunday newspaper.
"Mahmood has now been exposed by my lawyers openly lying to the judge and jury. These lies were told to stop crucial evidence going before the jury."
She added: "This evidence showed that I told Mahmood's driver that I disapproved of drugs, which is the truth.
"It is clear that the driver was pressurised to change his statement to strengthen Mahmood's evidence and cause damage to mine. Thankfully the lies have been uncovered and justice has been done."
It is not the first time a trial based on Mahmood's articles has collapsed.
While working for The News Of The World, he produced a splash that claimed there had been a conspiracy to kidnap Victoria Beckham and demand a ransom from her husband David.
But the trial of five men collapsed after the chief prosecution witness - Mahmood's main source - was deemed unreliable.