Boxing legend Muhammad Ali has been hospitalized with a respiratory issue, according to his spokesman. 

Bob Gunnell said Thursday that Ali, who has long battle Parkinson's Disease, is in 'fair condition' and being being treated by doctors as a precaution. 

He declined to say where Ali is hospitalized or when he was admitted. However, he did say that Ali's stay in hospital is expected to be 'brief.'

The three-time world heavyweight boxing champion's health has been fragile in recent years.

In January 2015 he was hospitalized with a urinary tract infection, and in late 2014 he was taken to hospital with pneumonia, but made a full recovery. 

And of course he has long been fighting Parkinson's Disease, early symptoms of which - including stuttering and trembling hands - began in 1979.

He retired from boxing in 1981 and devoted his life to social and humanitarian causes. In 2005 he was awarded the Presidential Medal of Freedom from President George W. Bush.

Ali was last seen in public in April, when he attended a Celebrity Fight Night charity event in Arizona.

(AP and Daily Mail)