British pop star George Michael was rushed to hospital last week (ends23May14) after falling ill at his home, according to U.K. reports. Two ambulances allegedly attended the former Wham star's north London home at around 8am on Thursday (22May14) after a concerned friend called emergency services. Witnesses claim the ambulances left after four hours with Michael on board, though the cause of his illness remains unknown. A spokesperson for the London Ambulance Service confirmed to Britain's Daily Mail newspaper, "We were called just before 8am on May 22. We sent two ambulance crews and staff treated one patient, a man, who was then taken to hospital." Michael's agent tells Britain's The Sun, "George Michael was in hospital for routine tests but there is nothing further to say." The 50-year-old Faith singer has been hit with a series of health problems in recent years. In 2011, he was hospitalised in Vienna, Austria with pneumonia and spent weeks in intensive care, and in May last year (13) he sustained head injuries after falling from a moving car on a British highway.