Madonna was rushed to hospital in New York City after she developed a "serious bacterial infection" which reportedly led to a stay in an intensive care unit.
The 64-year-old pop singer was due to start her world tour in July but that has now been postponed, the Mirror reports.
However, despite her several-day stay in the ICU her health is said to be improving and she is expected to make a "full recovery".
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Her manager Guy O'Seary shared the news in a statement on Instagram this evening, writing: "On Saturday, June 24, Madonna developed a serious bacterial infection which lead to a several-day stay in the ICU.
He continued: "Her health is improving, however she is still under medical care. A full recovery is expected. At this time we will need to pause all commitments, which includes the tour."
"We will share more details with you as soon as we have them, including a new start date for the tour and for rescheduled shows."
Madonna's upcoming Celebration tour - which was announced earlier this year - had been due to launch next month and set to conclude in January next year.
The global tour was set to feature four decades of her greatest hits and will see her visit 35 cities over the course of seven months.
It was due to launch in Vancouver, Canada on July 15, before heading to venues in the US, the UK, Sweden and other countries, ahead of the tour concluding with a series of concerts in Mexico next year.
The pop sensation didn't have any dates scheduled in Ireland but was due to play several nights at London's O2 Arena starting in October.
It's not known which dates of the tour will be affected or whether the entire tour is being delayed.
The tour is expected to celebrate her decades-long career in the music industry, which has included numerous chart-topping singles such as Like a Prayer, Vogue and Into the Groove.