Tulisa Contostavlos has urged police to investigate undercover reporter Mazher Mahmood - known as the 'Fake Sheikh - and "put an end to his deceits".
She was speaking after her trial on drugs charges collapsed with the judge telling jurors there were "strong grounds to believe" that Mr Mahmood had "lied" at a pre-trial hearing.
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Political parties across the country suspended their General Election campaigns following the Manchester Arena terror attack on Monday.
Investigators believe Mr Kushner has significant information relevant to their inquiry, officials told NBC News.
The men were detained as part of an investigation by MI5 and the Metropolitan Police's Counter Terrorism Command.