Sinead O'Connor recently wrote and posted her fifth open letter to Miley Cyrus, in which she urges the 20-year-old pop star to apologize for mocking people with mental illness, JustJared reports.

The feud began when O'Connor penned an open letter to Cyrus, urging her not to let the music business make a "prostitute" of her, as it doesn't "give a s***" about artists." O'Connor's original letter acknowledged Cyrus's talent and how the former Disney star paid homage to her "Nothing Compares 2U" video with her latest, "Wrecking Ball," though O'Connor remained intent on proving her point.

"I am 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," O'Connor wrote. "It is in fact the case that you will obscure your talent by allowing yourself to be pimped, whether it’s the music business or yourself doing the pimping."

Cyrus's response was to mock O'Connor, comparing her to troubled actress Amanda Bynes, who is currently seeking psychiatric treatment. She included older tweets of O'Connor's that the Irish singer and songwriter had made, suggesting a parallel between Bynes and O'Connor's Twitter rants.

This infuriated O'Connor, as the Irish singer struggles with bipolar disorder. She wrote a follow-up open letter encouraging Cyrus to "wake up and apologize" to those she may have offended with her latest antics. "I hope that you will apologize to Amanda Bynes and to any person who has been wounded by your mockery of those who have suffered," O'Connor wrote.

 "I don't have time to write you an open letter cause I'm hosting & performing on SNL this week," Cyrus tweeted in response, posting a photo of O'Connor ripping up a picture of the Pope during an SNL skit in which she was protesting the abuse prevalent in the Catholic church.

"Miley, I have no interest whatsoever in meeting you," O'Connor wrote in a third open letter on Oct. 4. "You had plenty of time yesterday to abuse Amanda Bynes...an entirely innocent party...and myself...who also did nothing to deserve your abuse, along with every other sufferer of mental health problems and every person who suffered abuse at the hands of priests."

Reportedly, the latest response from Cyrus was to ask O'Connor if they planned to kiss if they decided to make up.

Here is Sinead O'Connor's fifth and latest open letter for Miley Cyrus in response to her latest comments:

Dear Miley

I hear you’ve asked “Are we supposed to kiss?”.. when someone asked you would we ‘make up’. No, worry not.. there’s no need for kissing.. But let me state again.. You’re supposed to apologise for the mocking of any person who sought help, publicly or privately, to prevent themselves from committing suicide.
You’re also supposed to apologise for mocking people who are mistakenly or otherwise perceived to be mentally ill. Because what you did is extraordinarily dangerous as it contributes to the silences which allow suicide to flourish and also contributes to the bullying of people perceived mistakenly or otherwise to be mentally ill. That bullying causes suicides. Thats why you’re supposed to apologise. Its really very simple. People die every day because of the type of thing you did.
Its not that hard to say sorry. Doing so will save lives.

Sinead.