English pop star George Michael was reportedly rushed to hospital after suffering a mystery collapse.

The 50-year-old was said to have suffered a 'mystery collapse' and a worried friend called 999, local reports said Thursday.

This comes as the latest for Michael who suffered a string of health scares through the recent years.

"We were called just before 8 a.m. on May 22. We sent two ambulance crews and staff treated one patient, a man, who was then taken to hospital," a spokesman for the ambulance service said, according to the Daily Mail.

Witnesses said the ambulances left four hours later with Michael on board. He was taken to a London hospital for emergency treatment.

Last night, his agent told The Sun's Chris Pollard: "George Michael was in hospital for routine tests but there is nothing further to say."

In 2013, the English singer suffered a head injury when he fell off a moving car and was airlifted to the hospital.