Sinead O'connor made headlines this week after penning an open letter to pop star Miley Cyrus in which she pleaded with the starlet not to prostitute herself for the music industry's gain. In response, Miley appeared to mock O'Connor, comparing her to Amanda Bynes, the actress currently in rehabilitation for mental issues. 

Miley CyrusMiley Cyrus Appeared To Mock Sinead O'Connor

In the original blog post on her website, O'Connor told Cyrus that she was "extremely concerned for you that those around you have led you to believe, or encouraged you in your own belief, that it is in any way 'cool' to be naked and licking sledgehammers in your videos," adding that Miley will "obscure your talent by allowing yourself to be pimped, whether it's the music business or yourself doing the pimping."

On Thursday morning, Cyrus appeared to respond to the letter, firstly by saying "Top of the mornin to ya :)" and then taking a screenshot of O'Connor's old Twitter posts in which she asked for help finding medical help. Miley said, "Before Amanda Bynes there was.."

"Sinead. I don't have time to write you an open letter cause Im hosting & performing on SNL this week," continued Miley, referencing her forthcoming Saturday Night Live appearance which will almost certainly be dreadful. "So if youd like to meet up and talk lemme know in your next letter," she added.

In response, Sinead posted another open letter, writing, "Miley... Really? Who the f*** is advising you? Because taking me on is even more f*****' stupid than behaving like a prostitute and calling it feminism. You have posted today tweets of mine which are two years old, which were posted by me when I was unwell and seeking help so as to make them look like they are recent. In doing so you mock myself and Amanda Bynes for having suffered with mental health issues and for having sought help."

Watch Miley Cyrus in the video for Mike Will's Made-It:

"Remove your tweets immediately or you will hear from my lawyers. I am certain you will be hearing from all manner of mental health advocacy groups also. It is not acceptable to mock any person for having suffered." 

Cyrus also pointed to the infamous 1992 incident in which O'Connor ripped up a photo of Pope John Paul II on Saturday Night Live.

Sinead O'Connor's website is currently down, though her response to Miley's tweets were reproduced on the Evening Standard's website, among others.