Madonna has voiced her disapproval of Instagram's rules on nudity.

The website has often come under fire for not allowing photos of female nipples.

This promoted the Free The Nipple campaign, which has been supported by a host of celebrities.

Madonna posted an old topless photo on the site recently before it was removed.

This irked the Queen of Pop, who later uploaded a censored topless photo and added:

"Why is it ok to show a** but not breasts? Drowning in the hypocrisy of social media #artforfreedom #Unapologeticb*tch #rebelheart."

The 56-year-old meanwhile released her latest album 'Rebel Heart' earlier this year.

Follow us: @Pressparty on Twitter / Pressparty on Facebook.

Watch Madonna perform live below: