A US federal judge has given Apple final approval for its settlement of $450m to resolve claims it harmed consumers by conspiring with five publishers to artificially inflate ebook prices.

According to Reuters, US District Judge Denise Cote approved - during a hearing in Manhattan - what she called a "highly unusual" accord, calling for the Cupertino firm to pay $400 million to 23 million consumers.

The settlement will mean Apple pays $400m to cover refunds for readers who purchased titles from its iBooks online store. The iPhone maker will also have to fork out $50m towards lawyers' fees.

However, there's still time for the company to appeal the ruling but the court, which will hear Apple's challenge on 15 December, apparently is not expected to change its previous ruling.

The case first hit the headlines in 2010 when the US Department of Justice (DoJ) accused Apple and five publishing companies, including Hachette and HarperCollins, of colluding to fix the price of books through Apple's ebooks service.

The case centered around accusations that Apple and the publishers vowed to charge either $12.99 or $14.99 for the most popular ebooks, above the $9.99 that Amazon would sell them for.

Over time all the publishers involved settled with the DoJ but Apple vowed to challenge the case. Cote found Apple guilty in 2013, and at the time said it was clear that Apple had known this tactic was illegal but had pressed ahead anyway in order to capitalise on the market demand for its platforms from publishers.

During Friday's hearing, Cote said it was an "unusually structured settlement, especially for one arrived at on the eve of trial."