A US judge has declared a mistrial in the Bill Cosby sex assault case after the jury remained deadlocked for days.

The seven men and five women were unable to reach a unanimous decision after some 53 hours of deliberations in Norristown, Pennsylvania.

Mr Cosby, 79, is accused of drugging and sexually assaulting Andrea Constand in 2004. His lawyers had argued the sex was consensual.

The US comedian could now face new proceedings.

He walks away from court a free man, but the prosecution has already said they are pursuing a fresh trial.

Dozens of women say he assaulted them, but statutes of limitation rules mean he was allowed to be tried for Ms Constand’s allegation only.

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The veteran entertainer could have faced up to a decade in prison if found guilty of three counts of aggravated indecent assault, which allegedly took place at his Philadelphia home 13 years ago.

Announcing the decision, Pennsylvania judge Steven O’Neill reminded Mr Cosby that he remains charged and on bail, despite the mistrial.

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One of Mr Cosby’s lawyers, Brian McMonagle, applauded the decision, saying: “The judge is right: justice is real.”

“We came here looking for an acquittal. But like that Rolling Stone song says ‘you don’t always get what you want’. Sometimes you get what you need.”

The district attorney who brought the charges, Kevin Steele, told reporters that the prosecution was seeking a retrial.

“We will evaluate and review our case. We will take a hard look at everything involved and then we will retry it. As I said in court, our plan is to move this case forward as soon as possible.”