South Korea's Psy says he will perform his hit Gangnam-Style topless if his song hits No. 1 on the US Billboard chart.

Psy's hit song, which mocks the rampant consumerism of a rich Seoul suburb, has gone viral on video-sharing website Youtube.

It has now been viewed more than 267 million times on Youtube since it was released in mid-July.

Wearing a formal shirt and undone bowtie, the 34-year-old busted out his Gangnam moves at the news conference.

Psy said Gangnam Style was "dress classy, dance cheesy".

Psy has already developed a cult following in South Koreay with his unique catchy beat, funny expressions, and kitsch appeal over the past 10 years.

Psy's hit became the first Korean song to top Apple's music download charts and he is now working with Justin Bieber's manager.