It was an elaborate and costly “sting”, involving flights to Las Vegas, a fictional £8 million movie deal and a string of five-star hotel suites.

But did the outcome - a Sun on Sunday splash headlined “Tulisa’s cocaine deal shame” and the arrest of its target on suspicion of assisting a drug deal - justify a complex entrapment operation which has led its victim to ask why she has become public enemy number one for the red-top tabloids?

Tulisa Contostavlos, the singer and former X Factor judge, is said to be in despair after becoming the latest victim of Mazher Mahmood, the mysterious investigative reporter known as the “fake sheikh”, due to his propensity for disguising himself in Arab robes to ensnare the credulous.

Download the new Independent Premium app Sharing the full story, not just the headlines

Mahmood’s latest trap was sprung at the Dorchester hotel, where Tulisa allegedly boasted that half of the names in her phonebook sold Class A drugs.

Tulisa, 24, who has publicly admitted dealing drugs as a teenager during a bad North London upbringing, said that she helped supply cocaine for friends and used a secret code with dealers, according to the Sun.

The N’Dubz singer passed on the phone details of a friend, who arrived at the hotel with half an ounce of class A drugs and sought £820 in payment.

The newspaper dutifully passed on a “dossier” about the drug deal to the Metropolitan Police, which arrested Tulisa and her friend, musician Mike GLC, on suspicion of plotting to supply Class A drugs.

However the newspaper was unable to catch Tulisa taking cocaine herself - she denied using the drug during the sting recordings – and the highly sophisticated operation which led up to the Dorchester entrapment suggests that the paper was seeking to expose behaviour which might have been even more damaging to the star.

In an operation, described by insiders as “risky” given the public interest defence which entrapment investigations must be able to demonstrate post-Leveson, Tulisa was initially duped into believing that she was being considered for an £8 million Bollywood film role.

The Sunday People claimed that she had been flown to Los Angeles and Las Vegas and introduced to her “co-stars” in the penthouse of a five-star hotel.

Daily coronavirus briefing No hype, just the advice and analysis you need Enter your email address Continue Continue Please enter an email address Email address is invalid Fill out this field Email address is invalid Email already exists. Log in to update your newsletter preferences Register with your social account or click here to log in I would like to receive morning headlines Monday - Friday plus breaking news alerts by email Update newsletter preferences

The hoax climaxed in the Mayfair hotel, where the “film producers” asked if Tulisa was able to supply drugs.

A friend of the singer said: “She believed she was going to get this major role and contracts were being readied to sign. She was supposed to play a London street girl who goes to India. She was showing off her credentials to the producers by saying she could get drugs. She wanted the part.”

The friend added: “Is it any surprise that Tulisa knows people who can get drugs? She’s never made a secret that she used to live in a council flat with a dealer. This was a fishing expedition without justification. It’s hardly a story.”

The Sun, which says reports that it spent £100,000 on the operation and flew Tulisa around the world in a private jet are false, cited Tulisa’s claim that she was now a “role model” who had turned her back on the world of drugs, as justification for the story.

A spokesman for The Sun said: “The Sun’s investigation into Tulisa Contostavlos is justified in the public interest. We have handed our dossier of evidence to the police. We observed the PCC Code throughout the investigation and only used subterfuge because there was no other means of securing proof.” No money was offered to Tulisa for any film deal by The Sun, the paper said.

Tulisa’s team, who will consider legal action against the newspaper if the performer is cleared, believe that an element of the tabloid press is determined to destroy her.

Born into a Greek-Cypriot/Irish family, Tulisa’s rise from troubled council estate teen, who suffered from mental health and drug issues, to mainstream entertainer living in a £6 million Hertfordshire home, has been accompanied by taunts that she is the “queen of the chavs” who dared to rise above her status.

She won fresh admirers for forcing ex-boyfriend Justin Edwards to admit in court that he tried to make money out by publishing mobile phone footage of the couple having sex, quashing false claims that she may have leaked the footage as a publicity stunt.

Her business interests, which include a perfume and clothing range, as well as a novel due to be published in the Autumn are now at risk. “Tulisa could lose her endorsements and her entire career is under threat until the drugs case is cleared up,” the friend said. “It’s just playing with someone’s life. Is the ultimate story that they want her to kill herself? A weaker person might do something stupid.”

A spokesman for Tulisa said she was unable to comment whilst the Police investigation was on-going. She intends to tell her side of the story, if she is cleared.

Mahmood, former Investigations Editor at the News of the World, the Sun on Sunday’s predecessor which closed in 2011, was criticised for telling the Leveson Inquiry that his journalism had led to in excess of 260 criminal prosecutions. An independent inquiry found evidence of 94 individual convictions.

Since moving to The Sun, a Mahmood investigation has resulted in the former world boxing champion Herbie Hide facing a prosecution for conspiracy to supply cocaine. A Sun story in February told how Hide allegedly arranged to supply cocaine and threatened to throw a fight for a total of £1 million.

Mazher Mahmood profile:

Dismissed from the Sunday Times in 1988 for tampering with a computer in order to cover up a mistake.

Wins “Reporter of the Year” award in 1999 for exposing Newcastle United bosses Freddy Shepherd and Douglas Hall, who mocked fans and called Geordie women “dogs”.

Countess of Wessex accused of exploiting her Royal contacts to attract business for her PR firm after Mahmood approaches her, disguised as a wealthy sheikh, in News of the World operation.

In 2006 England head coach Sven-Göran Eriksson revealed that he planned to leave England to become Aston Villa manager, and would approach David Beckham to become captain after Mahmood approach, posing as a businessman.

Denies in court that NotW investigation which exposed spot-fixing by Pakistan cricketers stemmed from hacking into mobile phones. Three cricketers received custodial sentences after 2010 scandal.

Jockey Kieren Fallon, who won damages and an apology from the News of the World following a Mahmood investigation, told Channel 4: “They destroy people's lives. I was suicidal about it and you can't put a price on that.”

Claims that Mahmood’s 20-year investigative career led to more than 260 “successful criminal prosecutions” rejected by Linklaters which reduced figure to 94 after internal inquiry by then Sunday Times editor, John Witherow.