Leona Lewis and Simon Cowell have become the victims of the highest-profile hacking case the music industry has ever seen.

The onetime X Factor winner turned worldwide singing star has had three tracks stolen and leaked on to the internet after hackers tapped into the IT system of Syco Records, the label run by music mogul and TV talent show judge Cowell.

The latest track to be posted on the web, Don’t Let Me Down, was produced by the Grammy Award-winning performer Justin Timberlake.

All three tracks were made during recording sessions for Lewis’s new album, due out in November.

Fellow X Factor winner Alexandra Burke has also been targeted by the Syco hackers, who have stolen and released several songs the singer recorded as she worked on her forthcoming debut album.

The International Federation of the Phonographic Industry (IFPI) said it was the highest-profile hacking case the music industry had ever seen.

Jeremy Banks, the head of the organisation’s internet anti-piracy unit said: “IFPI is working with Syco and law enforcement agencies in the US and Europe to trace the individuals who stole the Leona Lewis/Justin Timberlake track.”

The police are understood to have been tracking the hackers for several weeks and are close to closing the case.

“They have a significant list of names and there are a couple of ringleaders,” a source close to the case told Times Online.

Syco Records has had difficulty pinpointing exactly when the thefts took place or if Lewis and Burke’s tracks were stolen at the same time as the hackers have fed the songs to the internet over a period of time.

The label has since changed its IT systems, removing all music from the holding site that was targeted.

Syco spokeswoman Ann-Marie Thomson said that while the leaks were touted as coming from Lewis’s forthcoming album, the songs were demo versions and the singer had yet to decide whether they would be included on her forthcoming release.

“They record an awful lot more songs than end up being used.

“Any artist feels very protective of their music and don’t want unfinished versions being heard,” she said.

The IFPI said that while traditionally music leaks have come from the theft of physical copies of CDs or records, it has seen other record companies hacked.

“Pre-release leaks, however they are sourced, are highly damaging to our members who invest considerable budgets in marketing and promoting music ahead of release,” Banks said.

Lewis’s album is expected to be one of Britain’s biggest-selling records of the year after her debut effort, Spirit, topped music charts around the world in 2008. The album also saw the Londoner nominated for three Grammys and become the first British woman in 20 years to top the American charts.

The targeting of such a high-profile star is a blow to the music industry, which is engaged in a long-running battle to stamp out internet piracy.

File sharing sites have been widely blamed for the flagging profits of record companies, with the British Phonographic Industry (BPI) estimating that the industry lost £180 million to online music piracy last year.

According to the IFPI, 95 per cent of all music downloads are illegal.

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