British singer George Michael performs on stage during his concert at Czech State Opera House as a part of "Symphonica: The Orchestral Tour" in Prague August 22, 2011.[Photo/Agencies]

British singer George Michael has postponed a series of concerts after falling ill with pneumonia, his website said on Wednesday.

The 48-year-old former Wham! frontman called off a planned gig in Vienna on Monday and another in Strasbourg on Wednesday, and now his Cardiff dates have been put on hold.

"With great regret, George Michael has been forced to postpone his November 26 and 27 shows in Cardiff, Wales, due to his ongoing illness.

"George was recently forced to postpone tour dates in Vienna and Strasbourg under doctor's orders after being diagnosed with pneumonia. He is currently receiving treatment," a statement read.

Michael, whose chart-topping hits as a solo artist include "Faith" and "Careless Whisper", also announced that an earlier cancellation, an October 26 concert at London's Royal Albert Hall, would be rescheduled for May 2, 2012.

Details of other postponed shows will follow.