NEW YORK (AFP) - The outspoken Irish singer Sinead O'Connor on Wednesday cancelled all upcoming shows citing exhaustion and an unspecified medical condition.

O'Connor apologised "profusely" to fans in a statement that said she was "completely unable to travel and perform."

"She is suffering from exhaustion due to an existing not-resolved medical situation and she has been advised by the doctor to stop any activity and rest," her agent said in a statement.

Her scheduled dates had included headlining appearances on Thursday at the Galway International Arts Festival in Ireland and at next month's Edmonton Folk Festival in Canada.

O'Connor earlier this year announced that she would stop performing her most identifiable song, the Prince-written Nothing Compares 2 U, as she no longer felt an emotional connection.

The 48-year-old artist is known for her strong views on issues including women's rights and abuses of the Roman Catholic Church.

She recently stirred debate by blasting Rolling Stone, generally considered one of the most influential music magazines, for putting celebrity socialite Kim Kardashian on the cover.

"Music has officially died. Who knew it would be Rolling Stone that murdered it?" she wrote on Facebook.