Aguilera, 30, had performed with scantily clad dancers on the UK finale, and Barbados singer Rihanna had also performed a raunchy routine when she stripped off her gown to parade around the stage in a bikini.

The show, which had been watched by nearly 18 million people, had UK's biggest television audience of the year, the Sydney Morning Herald reported.

Ofcom received around 2750 complaints about the pre-watershed scenes and broadcaster ITV had more than 1000.

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 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.