X Factor viewers will be able to vote for free for the first time in the latest series.

An app will allow fans to back their favourite acts once the show, which returns this weekend, reaches the live shows stage.

Those with tablets and smartphones running Apple's iOS and Google's Android software can download the free app.

Viewers will be able to cast up to five votes whenever the polls are open and they can back one contestant or a combination.

It is the first time voting for contestants has been available free of charge since the ITV show arrived in 2004.

Each vote cast on a BT landline or a mobile phone cost 35p during previous series.

Ann Cook, of ITV, said: "Having successfully launched in-app voting for The X Factor last year, we know there's a growing appetite for viewers to engage with the show via a digital platform.

"The new initiative to offer in-app voting for free centres around our ambition to give viewers new and exciting ways to interact with our shows, and explore how a mixed economy of free and paid voting drives interactive behaviour."

Kat Hebden, of FremantleMedia UK Interactive, which co-produces the show with Syco Entertainment, said: "The introduction of free in-app voting on The X Factor will be a real game changer in terms of how people interact with the show and we're looking forward to a fantastic series."

Mark Brittain, of Syco, said: "We are constantly looking to innovate around the show. Giving the viewers the ability to vote free through the app will allow viewers, we believe, an even greater opportunity to interact with their favourite show and, of course, play the hugely important role in deciding the ultimate winner of the series."