Los Angeles, Jan 4 (IANS): Pop star Madonna has apologised for posting altered photographs of anti-apartheid icon Nelson Mandela and activist Martin Luther King Jr. to promote her new album.

“I'm sorry. I'm not comparing my self to anyone. I'm admiring and acknowledging there (sic) Rebel Hearts," Madonna posted on her official Facebook page, reports dailymail.co.uk.

The 56-year-old's cover for the album “Rebel Heart” is a close-up of her face with black string on it.

Her social media posts show the faces of King and Mandela doctored to make it appear as though they have similar string on their faces. Some consider the posts offensive.

She said: “This is niether a crime or an insult or racist! I also did it with Michael jaclson and frida khalo and marilyn monroe (sic)."

“Am I saying I am them NO I'm saying they are Rebel Hearts too. And I didn't do it My fans did And I just re posted those photos My fans aren't racist either If they put me in the same category as these other people Thank you."

“I'm very flattered and I hope one day to live up to 1 100th of what those people accomplished.”