SEOUL, June 24 -- Former NCT member Mark has apologised after photographs of him wearing a T-shirt featuring the Confederate flag sparked criticism online.

In a statement posted on social media today, Upper Room - the creative agency Mark established earlier this month - said it was "deeply sorry" for the concern and disappointment caused by the vintage T-shirt, which carried imagery widely associated with racism and white supremacy in the United States.

The apology came after images of the singer wearing the shirt spread across online communities, with many users pointing out that the Confederate flag remains a highly controversial emblem because of its links to slavery, racial segregation and extremist groups, according to The Korea H...