Ant McPartlin and Declan Donnelly are unable to hide their shock when a performer strips naked on the stage in a bizarre yet hilarious routine in the first episode of Britain's Got Talent.

In a preview released ahead of Saturday's launch show, the presenting duo are seen watching from the side of the stage as an act called Mr Uekusa shows off his unique skills to judges Simon Cowell, David Walliams, Alesha Dixon and Amanda Holden.

Mr Uekusa, who describes himself as an "international variety performer" starts off his routine by pulling all of his clothes off, apart from his underpants and a bow tie.

He puts sheer tights over his face and positions a glass of liquid on them before pulling the hosiery off quickly, keeping the beverage firmly in place.

Mr Uekusa then achieves a similar feat with a glass balanced on a piece of plastic, resting on plungers stuck to his chest.

But his most surprising moment comes when he covers himself with a small piece of fabric and swiftly removes his underpants on the stage.

As Walliams falls about in hysterics, Ant and Dec - who have a clearer view of the performer's naked body - laugh and shield their eyes, stunned.

Mr Uekusa's crowning moment comes when he lies on the floor, covers himself with the fabric and positions three tea cups and saucers on his body.

Then, to rapturous applause and laughter from the audience, he whips the material out from under him, with one of the items of crockery sitting on his groin.

The preview shows McPartlin hosting the pre-recorded auditions for the ITV show along with presenting partner Donnelly.

The first episode of Britain's Got Talent will see him return to TV screens for the first time since he stepped down from his TV commitments, after being charged with drink-driving last month.

He is expected to appear throughout the auditions, which run to the end of May, but will be absent from the full week of live shows.

ITV previously confirmed that Donnelly will be hosting the live shows solo, after he presented the final two episodes of the duo's Saturday Night Takeaway without his TV partner of almost 30 years.