George Michael was taken to hospital last week by ambulance after falling ill, it has emerged.
The 50-year-old fell ill and two ambulances were sent to his north London mansion following a 999 call by a worried friend.
His agent told The Sun in a statement: "George Michael was in hospital for routine tests but there is nothing further to say."
A London Ambulance Service spokesman said: "We were called just before 8am on May 22. We sent two ambulance crews and staff treated one patient, a man, who was taken to hospital."
George - whose real name is Georgios Kyriacos Panayiotou - nearly died from pneumonia in late 2011.
In May last year he was treated in hospital for injuries following a bizarre incident on the M1 motorway. He was airlifted to hospital with a head injury after falling from his vehicle on to the road.
Just 18 months earlier the troubled singer had been close to death after being struck down with pneumonia in Vienna, but he fought back to perform again.
George, whose hits include Careless Whisper, Faith and Freedom, has had health scares and run-ins with the police linked to his drug use.
In September 2010, he received an eight-week prison sentence following an incident the previous July in which he crashed his Range Rover into a shop in north London.
He was also given a five-year driving ban after he pleaded guilty to driving under the influence of drugs and possessing cannabis.
And he had earlier been banned from driving for two years and sentenced to 100 hours of community service in 2006 when he was convicted of driving while unfit through drugs after he was found collapsed in his Mercedes.
Following his brush with pneumonia in late 2011, the star made a tearful appearance outside his London home after flying back into the country and said it had been ''touch and go'' whether he lived.
Doctors had performed a tracheotomy to keep his airways open and he was unconscious for some of his spell in hospital.