Madonna apologised last night after she provoked outrage by using a racial slur to describe a picture of her son.

The singer posted a picture of her 13-year-old son Rocco boxing on photo sharing site Instagram, along with the tag #disni**a.

Moments later, the photo was taken down after criticism from her followers, some of who accused the 55-year-old star of racism.

Madonna later defiantly reposted the picture, along with the caption "Get off my d*** haters."

Later, Madonna issued an apology for using the offensive term, and deleted the posting altogether.

"It was used as a term of endearment toward my son who is white. I appreciate that it's a provocative word and I apologise if it gave people the wrong impression," she said in a statement.

"It was not meant as a racial slur. I am not a racist. There's no way to defend the use of the word."

Rocco is Madonna's son with film director Guy Ritchie.