Park Jae-sang, otherwise known as Psy, made the apology on Friday evening, after reports surfaced that he had taken part in two 2004 concerts that criticized the US military.

In one of the concerts, Psy protested about the deaths of South Korean girls who were run over by a US tank stationed in the country. The other saw him rap about killing "Yankees" who tortured Iraqi captives and their families.

Psy said the lyrics were part of a "deeply emotional" reaction to both the war and the girls' deaths.

"While I'm grateful for the freedom to express one's self, I've learned there are limits to what language is appropriate and I'm deeply sorry for how these lyrics could be interpreted," said Psy. "I will forever be sorry for any pain I have caused by those words," he added.

The artist is scheduled to perform at the annual "Christmas in Washington" television special, which is to be attended by Obama and his family. The broadcaster TNT said that Psy would still perform as planned.

Pys's "Gangnam Style" pop and dance video has now become the most-watched video ever, garnering more than 900 million views since it was first uploaded in July.

rc/jm (AP, Reuters)