The populist leader of oil-rich Venezuela became Latin America's most vocal and controversial leader and was Washington's chief antagonist in the region.
The Venezuelan government had said earlier Tuesday that a severe new respiratory infection had hit cancer-stricken Chavez and his condition was "very delicate."
The government had said Chavez had been undergoing "chemotherapy of strong impact."
Chavez had neither been seen nor heard from, except for photos released in mid-February, since submitting to a fourth round of surgery in Cuba on Dec. 11 for an unspecified cancer in the pelvic area. It was first diagnosed in June 2011.
The government had said he returned home on Feb. 18 and was confined to Caracas' military hospital since.