V Festival organisers are hoping Cheryl Cole will still perform at the event, saying they have not been told that she is pulling out.
Their comments came as Cole, who has been diagnosed with the potentially deadly disease malaria, has been moved from a private clinic to receive specialist care.
The singer was transferred to University College London (UCL), which is home to the Hospital for Tropical Diseases, in the centre of the capital.
A spokeswoman for UCL confirmed that Cole was being treated at the Trust.
The star is said to have spent two hours in intensive care at an emergency unit of the Cromwell Hospital before being moved.
Cole, 27, has pulled out of the last in the current series of 'X-Factor' auditions while she fights the potentially deadly disease malaria.
An 'X-Factor' spokeswoman said: “We’re not due to film with Cheryl again for a few weeks, so we will just keep in touch with her to see how things are going.”
A spokesman for the V Festival, where she is set to perform high-profile shows, said: “V Festival has not been informed by Cheryl Cole’s management that she will not be appearing at this year’s festival. Unless otherwise informed, organisers are expecting her to appear as planned and wish her a speedy recovery.”
The star contracted malaria on her trip last month to Tanzania – which is home to one of the most dangerous strains of malaria – despite taking malaria tablets.
The singer and close friend Derek Hough spent six days together on Africa’s east coast following her split from England footballer Ashley.
Cole, who has been supporting Black Eyed Peas on tour, is reported to have collapsed with suspected gastroenteritis during a photoshoot for her album on Saturday afternoon, when she was initially diagnosed with exhaustion.
But she was rushed to hospital the next day after her symptoms, including a soaring fever, worsened.
The next stage of the 'X-Factor' auditions will take place at the weekend without the star, with Pussycat Doll Scherzinger standing in for Dannii Minogue, who has just had her baby boy.
The Manchester session will be the final audition in the current series. Judges then have to film Boot Camp before the show goes live, usually at the end of August.
Malaria is caused by the parasite plasmodium, which is transmitted by the bites of infected mosquitos.
If not treated promptly, it can become life-threatening by disrupting the blood supply to vital organs.
Around 850,000 die of malaria annually around the world, mostly pregnant women and children under five in Africa.