A US judge has thrown out President Donald Trump's $10bn dollar lawsuit against The Wall Street Journal, ruling the suit was "grasping at straws".

Trump had sued the media outlet's parent company Dow Jones and its leader Rupert Murdoch last year after it reported on a letter allegedly written by Trump to disgraced financier and sex offender Jeffrey Epstein as part of a birthday book in 2003, before Epstein was charged with sex crimes.

Trump has denied writing or signing the letter, which included suggestive language and a drawing of the outline of a woman's body.

Judge Darrin Gayles threw out the case, finding the suit runs counter to the First Amendment, which protects freedom of the press.

Gayles had already once dismissed the defamation lawsuit, which sought $20 billion in damages.…