Miley Cyrus has responded to Sinead O'Connor's open letter to her by comparing her to Amanda Bynes on her personal Twitter page.

Last night O'Connor penned a letter on her personal blog warning Cyrus that "pop music will make a prostitute out of you", after Cyrus was quoted as saying that O'Connor's classic 'Nothing Compares 2 U' music video was the inspiration for her 'Wrecking Ball' video.

The 1000+ word plea from O'Connor goes on to detail her concern for Cyrus and that she has been falsely led to believe that appearing naked in music videos, or licking sledgehammers, is "cool" and doing so will ultimately "obscure [her] talent by allowing [her]self to be pimped."

Well, Cyrus has fired back and done so with rather classless gusto by comparing O'Connor to Amanda Bynes (who is currently seeking treatment for mental health issues) and then posting a screengrab of some tweets that O'Connor posted in 2012 (see below).

To make light of anyone's mental health, or to throw such accusations around, is a very low move and doing so in the most public of forums really illustrates Cyrus's unprofessionalism and ultimately confirms a lot of the assertions that O'Connor was making in her blog post.

Miley Cyrus, you're an absolute Idiot.