George Michael has postponed the rest of his 2011 tour dates.

The 'Freedom' hitmaker was hospitalised in Vienna, Austria with pneumonia earlier this week and has now scrapped the rest of his 'Symphonica' concerts in Europe, including three homecoming shows at London's Earls Court that were scheduled for December.

His doctors, Dr. Christoph Zielinski and Dr. Thomas Staudinger, said in a statement: "George Michael has severe community acquired pneumonia and is being treated as an inpatient. His condition has stabilised and he is responding to treatment.

"From the current point of view, the time until recovery cannot be estimated, but he will not be able to perform the rest of the tour. Besides medical treatment, complete rest and peace and quiet are mandatory."

Despite still being in hospital, the star's publicist has said he is "slowly improving".

His spokesperson added: "He is receiving excellent medical care; he is responding to treatment and slowly improving."

Promoters are working to re-schedule the dates "at the earliest opportunity".

Last month, George cancelled a show at London's Royal Albert Hall due to back problems, a viral infection and high temperature.

The concert has been rearranged for May 2012.