Irish Prime Minister Leo Varadkar led tributes to the Dublin-born star, saying her music was "loved around the world and her talent was unmatched and beyond compare".

In a tweet, Irish mixed martial artist Conor McGregor - who was once welcomed into the ring with O'Connor's voice before a UFC fight - said "the world has lost an artist with the voice of an angel".

He added: "Ireland has lost an iconic voice and one of our absolute finest, by a long shot. And I have lost a friend.

"Rest In Peace, Sinead you are home with your son I am sure."

O'Connor's 17-year-old son Shane died by suicide last year. The Nothing Compares 2 U singer said in a tweet posted just nine days ago that she had been living like an "undead night creature" since his death.

Further tributes rolled in from musicians from all genres, with Bryan Adams saying how much he "loved working with [her] making photos, doing gigs in Ireland together and chats".

Rapper Ice-T said the singer "stood for something... unlike most people", Ian Brown of rock band The Stone Roses wrote that collaborating with O'Connor was "magical" and 1990s indie group Massive Attack said the band was "devastated" by her death.

Scottish First Minister Humza Yousaf reflected on the "sad news" on Twitter, using the singer's Islamic name.

"Sinéad/Shuhada was a unique musical talent who undoubtedly inspired many people to speak about their own mental health by being so open about her own struggles," he wrote. "Condolences to her family, friends & all those who loved her."

Mr Yousaf finished his tweet with a verse from the Koran commonly used when someone has died - referencing the singer's conversion to Islam in 2018.

Meanwhile, the singer Alison Moyet said O'Connor's voice "cracked stone with force & by increment".

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She added: "As beautiful as any girl around & never traded on that card. I Loved that about her. Iconoclast."

O'Connor's distancing from the pop mainstream, including her shaved-head look and boycotting of awards, gained her admirers far and wide.

One of her more recent ventures included working on historical drama Outlander where she was the voice of the opening credits for season seven.

Bear McCreary, the composer of the show's score, tweeted that he was "gutted by the loss", calling her a "warrior poet".

McCreary revealed he had teamed up with O'Connor "writing new songs together, which will now never be complete" and ended his tribute with: "We've all lost an icon. I've lost a friend."