She was best known for her 1990 song Nothing Compares 2 U - the track made her a global star, partly due to its iconic video.

A family statement said: "It is with great sadness that we announce the passing of our beloved Sinead.

"Her family and friends are devastated and have requested privacy at this very difficult time."

No cause of death was given.

Live - Tributes to an 'unmatched talent'

Irish Prime Minister Leo Varadkar tweeted: "Her music was loved around the world and her talent was unmatched and beyond compare."

Singer Alison Moyet tweeted she had a "voice that cracked stone", while ex-Stone Roses star Ian Brown said working with her was "a highlight of my musical life".

Bryan Adams posted a picture of O'Connor and said he "loved" working and chatting with her.

Irish UFC star Conor McGregor also shared images and said Ireland had "lost an iconic voice and one of our absolute finest".

The singer was known for her outspoken views on subjects such as religion, war and feminism.

She infamously tore up a photo of the Pope on Saturday Night Live in 1992 to protest against abuse in the Catholic Church.

O'Connor converted to Islam in 2018 and changed her name to Shuhada Sadaqat, but still performed under her old name.

The singer cancelled gigs in 2021 after announcing she was entering a one-year programme for trauma and addiction.

The following year her 17-year-old son Shane died by suicide.

O'Connor referenced his death in an emotional tweet last week in which she said she was "lost" without him.

She posted a row of crying emojis alongside a photo of the pair and said she had been "living as undead night creature since [his death]"

"He was the love of my life, the lamp of my soul. We were one soul in two halves," she wrote.

The singer recorded 10 studio albums and was nominated for eight Grammys, but never topped the huge success of Nothing Compares 2 U - originally written by Prince.

The intense close-up of the singer - and her tear during the video - is instantly recognisable to a generation of fans.

She once said she had shaved her head in response to music bosses pressuring her to be conventionally glamorous.

O'Connor began playing on the streets of Dublin using a guitar given to her by a nun and released debut album The Lion and the Cobra in 1987.

Her last record, I'm Not Bossy, I'm The Boss, came out in 2014.

"Everyone wants a pop star, see?" she wrote in her memoir two years ago. "But I am a protest singer. I just had stuff to get off my chest. I had no desire for fame."

She was married four times - the final one ending after 16 days in 2011 - and had four children.