George Michael is "improving steadily", his doctors have said.

The 48-year-old singer fell ill with pneumonia in Vienna, Austria, last week. He then reportedly developed a secondary breathing condition and has been treated in intensive care.

There has been speculation that George is gravely ill, but the medical team treating him have assured fans he is getting better.

"The latest development in Mr. Michael's case - which has evolved from a severe pneumococcal infection - necessitated intensive care due to its severity and extension," Professors Gottfried Locker and Christoph Zielinski said in a statement.

"We are happy to announce that Mr. Michael is improving steadily with an impressive regression of pneumonic symptoms and follows a steady rate of improvement as hoped.

"As we said previously, complete rest and peace and quiet are mandatory."

George was forced to postpone the rest of his Symphonica world tour after his hospitalisation.

A statement on his website has assured concert-goers that "discussions and preparations" are already being made to reschedule the dates, although they won't happen until the star is fully recuperated.

When he first fell ill there were rumours George had a heart condition, but his doctors have been keen to allay people's fears about it.

"There are no other health issues with regards to the patient other than the underlying pneumonic disorder, and no further measures had to be taken," the statement continued.

"Mr. Michael is receiving precisely the same treatment as any ordinary patient in Austria would receive at the hospital for this disease."