The newly-crowned Miss Teen USA Karlie Hay has apologised for the "careless" racial slurs she used during her youth.

Controversy rained down on Hay shortly after she was crowned the winner of the 2016 contest on Saturday (30Jul16) after a number of her social media posts from 2013 resurfaced online.

In the questionable tweets, Hay openly cursed and used threatening language, while repeatedly including the N-word, but now, three years later, the 18-year-old claims she has seen the error of her ways.

"I am very sorry. It's embarrassing," Karlie told breakfast show Good Morning America. "It's something I'm ashamed of and I've grown up from that 15-year-old girl who used that type of language."

The Texas native, who was crowned during a ceremony in Las Vegas, goes on to add: "At that age, I was being a follower. I was trying to fit in with my friends. The word was thrown around in the music I listened to, with the friends I hung out with and I had no guidance so it was kind of a careless mistake," she said.

"When the tweet got brought back up I was just like kind of embarrassed, ashamed, and just amazed that I actually at one point in my life thought it was OK to use that word because it's never OK."

Hay now hopes to use her own experience to educate others about offensive language.

Officials at the Miss Universe Organization, which operates Miss Teen USA, have condemned the "unacceptable" behaviour but have declined to strip Hay of her crown.