LOS ANGELES, June 3 (Xinhua) -- Boxing legend Muhammad Ali was in "very grave condition" as he was treated for respiratory trouble at a Phoenix, Arizona, hospital on Friday, report said.

An anonymous source told Agence France-Presse "the condition is very grave".

The heavyweight world champion, 74, was hospitalized on Thursday with a respiratory issue, which US media reported was complicated by his Parkinson's disease.