The online argument between Miley Cyrus and Sinead O'Connor has been hotting up and the 'We Can't Stop' beauty has now been slammed by a mental health charity for mocking O'Connor publicly on Twitter.

The feud began earlier this week when the 'Nothing Compares' star posted an open letter to Cyrus, in which she urged her to keep control of her career and to not allow herself to be 'prostituted' by the industry. Cyrus then hit back by mocking her online breakdown, which saw O'Connor. 

The director of Time To Change, Sue Baker, issued an official statement to the NME about Cyrus's recent comments and said: "It’s really disappointing to see Miley Cyrus mocking Sinead O'Connor's mental health problems and this only serves to fuel stigma."

"One in four of us will experience a mental health problem and there are times when we need to speak out and seek help."

"We would encourage Miley to apologise to Sinead for retweeting previous tweets that would seem to ridicule Sinead’s mental health issues."