X Factor's racy final involving Christina Aguilera will be investigated by Ofcom, the broadcasting watchdog has announced.
The show saw the US star perform a suggestive routine with scantily-clad dancers, while Rihanna also gave a raunchy performance when she stripped off her gown to parade around the stage in a bikini.
Ofcom received around 2,750 complaints about the pre-watershed scenes and broadcaster ITV had more than 1,000.
Aguilera's routine was the most explicit of the night, with her dancers wearing only stockings, knickers and bras.
Ofcom will assess whether the show broke section 1.3 of the broadcasting code, which states that “children must be protected by appropriate scheduling from material that is unsuitable for them”.
It announced earlier this month that it was assessing complaints and considering whether to launch a probe into the scenes.
An X Factor spokesman said at the time that it was “confident that the performances given by our guest artistes ... were appropriate for the show”.
A TV insider defended the final, saying that what was broadcast on the series, which ended with Matt Cardle taking the crown, was |no different to what is aired on music TV channels during the day.
The controversy was the latest surrounding this year's ratings-grabbing series of the X Factor.
Ofcom has previously announced it is investigating whether the show broke rules by encouraging viewers to download songs by guest stars Diana Vickers and Michael Buble.
The regulator is examining Simon Cowell's hit ITV1 show against rules in the broadcasting code on references made by broadcasters to commercial |products.