By Michael Holden

LONDON (Reuters) - British journalist Mazher Mahmood, renowned for his "fake sheikh" undercover sting operations for media mogul Rupert Murdoch's tabloids, was jailed for 15 months on Friday for tampering with evidence in a high-profile trial.

Mahmood, 53, whose elaborate disguises have duped criminals, celebrities, and even royalty, plotted to get his driver to change a police statement during the drugs prosecution of Tulisa Contostavlos, a singer and former judge of the British version of the "X Factor" TV talent show.

Contostavlos had been about to go on trial accused of supplying cocaine for Mahmood, the self-styled "King of the Sting", as he posed as an influential Indian film producer while working on an exclusive story for the Sun on Sunday paper.

The conviction is set to ruin the career of Mahmood, one of Britain's best-known undercover journalists. News UK, Murdoch's UK newspaper arm, said it had sacked him.

Some 18 individuals caught out by Mahmood's stings are planning to take civil action against him and lawyers are reviewing cases in which his evidence had led to successful criminal prosecutions.

"Mazher has led scores of successful investigations during his 25-year career with the company," a News UK spokesman said, adding any legal claims would be "vigorously defended".

"His work has led to the exposure of criminality and wrongdoing. It is a source of great regret that his time with the company should end in this manner."

Prosecutors said Mahmood got his driver, Alan Smith, to change a statement he gave to detectives which would have made Contostavlos's conviction less likely by supporting her case that she was a victim of entrapment. Her trial collapsed in July 2014 after questions arose about Smith's evidence.

Earlier this month both men were found guilty of conspiracy to pervert the course of justice at London's Old Bailey court and on Friday Mahmood was jailed for 15 months while Smith was given a suspended 12-month prison term.

Mahmood made his name at Murdoch's News of the World, which was closed in 2011 after it was revealed senior journalists had been hacking voicemails on mobile phones to get stories.

He carried out the undercover inquiry which led to the 2011 conviction of three Pakistani cricketers for taking bribes to fix incidents in a match against England and also duped Sophie, Countess of Wessex, wife of Queen Elizabeth's youngest son Prince Edward, in 2001 when he posed as an Arab sheikh.

But other stings have led to prosecutions which collapsed, including the case against five men accused of plotting to kidnap singer-turned-designer Victoria Beckham in 2002.

(Editing by Stephen Addison)