A teenage boy who translated all 759 pages of the latest Harry Potter book three months ahead of its official French release date has been arrested.

The 16-year-old was detained in Aix-en-Provence in southern France after he posted the unauthorised translation of Harry Potter and the Deathly Hallows on the internet.

Prosecutor Olivier Rothe said the student was held on Monday following a complaint from police in Paris and was released on Tuesday after questioning.

Mr Rothe said the boy could face charges for violating intellectual property rights. Police have since shut down the website.

The unofficial translation was available online within days of the July 21 publication of the English original.

The translation was not thought to have been produced for commercial gain.

The French version of the book - known as Harry Potter et les reliques de la mort - will not arrive in bookshops until October 26, as the official translator could only begin work after the release of the English original.