The new Miss Teen USA has been forced to apologise over racist tweets from her past just days after being crowned.

Karlie Hay won the pageant on Saturday but social media users quickly discovered an account under her name that featured tweets with the N-word from 2013 and 2014.

Pageant officials moved into damage control mode, saying in a statement that her language was "unacceptable at any age and in no way reflects the values of The Miss Universe Organisation".

They said the 18-year-old had been "in a different place in her life" when she posted the tweets.

"Karlie learned many lessons through those personal struggles that reshaped her life and values.

"We as an organisation are committed to supporting her continued growth."

Hay posted an apology on Twitter and Instagram, saying she had used language that "is not representative of who I am as a person".

It is understood that Hay, of Tomball, Texas, will be allowed to keep her crown.

She has promised to use her new position to advocate for those affected by drug and alcohol abuse. The pageant was owned by NBC Universal and the Republican Party's presidential nominee Donald Trump until Mr Trump made anti-immigrant remarks last year.

NBC and Spanish-language network Univision then refused to broadcast the show.

Mr Trump bought NBC's stake and in September he sold the whole pageant to talent agency WME/IMG.

Miss Teen USA also faced accusations of a lack of diversity after posting an image of the top five contestants on Twitter.

All five are white, with long blonde hair and light-coloured eyes.

Model Chrissy Teigen replied: "Wow how can we choose from such a diverse bunch."