The 64-year-old singer has been forced to postpone all forthcoming commitments, including The Celebration world tour, which had been due to kick off next month.

Her manager, Guy Oseary, said in a statement posted on social media: "On Saturday 24 June, Madonna developed a serious bacterial infection which lead to a several day stay in the ICU.

"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 soon as we have them, including a new start date for the tour and for rescheduled shows."

Responding to the news, numerous celebrities were quick to send good wishes to Madonna, with RuPaul's Drag Race judge Michelle Visage writing on Instagram: "Take good care of our queen".

Zooey Deschanel wrote: "Hope she feels better very soon!" while actress Rita Wilson said: "Sending Madonna my prayers for a speedy recovery."

Australian star Isla Fisher, who is married to British comedian Sacha Baron Cohen, added: "Sending her so much love from us," while Rosanna Arquette said: "Sending her love and good light vibrations for a good recovery."

Westworld star Evan Rachel Wood posted three heart emojis.

Madonna had been due to mark the 40th anniversary of her musical career with The Celebration world tour, which would have kicked off in Vancouver, Canada, on 15 July, before moving on to shows in the US.

She had been due to come to London for four sold-out shows at the O2 Arena from 14 October as part of the European leg of the tour.

Performances were also scheduled in Belgium, Denmark, Sweden, Germany and the Netherlands.

The show, which has been billed as a "one-of-a-kind experience," will feature music from her four-decade back catalogue.

Madonna last toured from September 2019 to March 2020 for her Madame X shows, however she was forced to cancel numerous dates of the run on "doctors' orders" after suffering "overwhelming pain".

At the time, she said she had been "plagued" with knee and hip injuries since the beginning of the tour, and was seen walking with a cane and wearing knee supports.

The first London show of the Madame X tour was one of those cancelled, with the star saying at the time: "I must always listen to my body and put my health first."

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The final two dates of the tour were later called off due to Covid, with the singer describing cancelling shows as "a kind of punishment for me".

Her Sticky & Sweet Tour, which ran from August 2008 to September 2009, and her 60-date Confessions tour in 2006 both broke records for the most money grossed on tour by a female entertainer ($194m and $411m respectively).

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Her tour record as highest-grossing female performer of all time was only broken last year, when she was overtaken by Taylor Swift's The Eras tour.

Known to many as the Queen Of Pop, the Grammy, Brit and Ivor Novello-winning star has reportedly sold more than 300 million records worldwide.

The singer - best known for a string of hits in the 1980s and 1990s including Like A Virgin, Vogue, Like A Prayer and Holiday - was inducted into the Rock & Roll Hall of Fame in 2008.