Image copyright Getty Images Image caption Rocco (right) is Madonna's only child with British film director Guy Ritchie

Pop star Madonna has apologised for using a racial slur to refer to her son on an Instagram post.

The singer uploaded a snapshot of 13-year-old Rocco Ritchie boxing on Friday night, with the offensive epithet used in a hashtag accompanying the photo.

"I am sorry if I offended anyone with my use of the 'n-word'," she said in a statement issued on Saturday.

It's a provocative word and I apologize if it gave people the wrong impression Madonna

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

Madonna's comment was swiftly deleted from her Instagram account after some of her 1.1 million followers berated her for using the hashtag "#disnigga"

She later re-posted the same photo on Instagram, with a defiant (and largely unprintable) new caption that began: "Ok, let me start this again."

On Saturday afternoon however, Madonna deleted the post entirely, and instead released a statement through her publicist, saying "forgive me".

"It was all about intention," she continued. "It was used as a term of endearment toward my son who is white.

"I appreciate that it's a provocative word and I apologize if it gave people the wrong impression."

Image copyright AFP Image caption Madonna and her children (L-R): David, Lourdes, Mercy and Rocco on a trip to visit the Mkoko Primary School in Malawi, funded by her Raising Malawi organisation

Besides Rocco, Madonna has three other children, including Lourdes, David and Mercy. Her two youngest were both adopted from the African nation of Malawi.

The star came under fire earlier this month for posting a separate picture of Rocco on New Year's Eve, in which he and his friends posed with bottles of alcohol.

Madonna responded: "No one was drinking, we were just having fun!

"Calm down and get a sense of humour! Don't start the year off with judgement!"