Singer Tulisa Contostavlos' trial on drugs charges has collapsed with the judge telling the jury it was likely a witness, an undercover reporter, had "lied".

Speaking after the trial, Ms Contostavlos urged police to investigate Mazher Mahmood and "put an end to his deceits".

The judge had said there were "strong grounds to believe" that Mr Mahmood had "lied".

The former X Factor judge condemned Mr Mahmood, known as the Fake Sheikh, for "openly lying" to the judge and jury.

Standing on the steps of London's Southwark Crown Court, the singer read out a statement saying: "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.

"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."

The Sun defended the original investigation but said Mr Mahmood had been suspended pending an internal inquiry.

A spokesman 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 CPS decision to prosecute.

"The Sun, of course, takes the judge's remarks very seriously.

"Mr Mahmood has been suspended pending an immediate internal investigation."