Miley Cyrus has hit back at Sinead O'Connor and invited her to a face-to-face chat.
Her offer for a meeting came after the Irish singer revealed she was "extremely concerned" about her Wrecking Ball music video and warned her not to be exploited by the music business, in an open letter on her website.
The 20-year-old mocked the Nothing Compares 2 U singer in a series of Twitter posts, likening her to troubled actress Amanda Bynes, who is undergoing psychiatric treatment.
She also hinted at Sinead's former health problems and posted a picture of her tearing up a photo of the Pope, as well as a screenshot of her older tweets from 2012, when she asked Twitter followers to recommend a psychiatrist.
Miley tweeted: "Sinead. I don't have time to write you an open letter cause I'm hosting & performing on SNL this week. So if you'd like to meet up and talk lemme know in your next letter. :)"
Sinead immediately wrote another open letter, and said she would sue the Hannah Montana star if she doesn't apologise publicly or remove the tweets.
"I have no interest whatsoever in meeting you. You had plenty of time yesterday to abuse Amanda Bynes.. an entirely innocent party.. and myself.. who also did nothing to deserve your abuse," the 46-year-old said.
"If you do not apologise I will have no choice but to bring legal proceedings against you, since it is extremely hard to be given work when people think one is suffering from mental illness. I have no interest in or desire to cause you trouble..."
She added: " I can't imagine your parents being at all proud of what you did yesterday."