The judge in the trial of Tulisa Contostavlos told the jury there were "strong grounds" to believe an undercover reporter had "lied" at a hearing before the trial began.
Judge Alistair McCreath was speaking as he threw out the case at Southwark Crown Court.
The Sun's Mazher Mahmood - known as the 'Fake Sheikh' - had posed as a wealthy film producer when he met Contostavlos at a number of hotels and restaurants.
The former N-Dubz singer strongly denied that she had helped broker a drug deal between Mahmood and her rapper friend Michael Coombs, also known as Mike GLC.
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Chancellor George Osborne will seek to reassure financial markets on Monday morning following Britain's decision to leave the EU.
In his first outing since the referendum result, the lead Leave campaigner has outlined his vision for a post-Brexit Britain.