Venezuelan President Hugo Chavez is "fighting for his life," the country's vice president said late Friday.
Chavez began chemotherapy after his fourth cancer surgery in Cuba in December, Vice President Nicolas Maduro revealed for the first time, and is continuing the "intense" treatment at a military hospital in Caracas.
The president, who announced his cancer diagnosis in 2011, spent more than two months in treatment in Cuba and has suffered respiratory insufficiency.
The government has never specified what kind of cancer Chavez has.
The president returned to Venezuela in late February after more than two months in Cuba, where he was treated for an unspecified cancer.
Mariano Castillo, Catherine Shoichet and Patrick Oppmann contributed to this report
His precarious health prevented Chavez from returning to Caracas for his inauguration on January 10.
While political opponents said that postponing the inauguration was unconstitutional, Venezuela's Supreme Court sided with Chavez's party, which argued that he did not need to be present at the swearing-in for his next term.
Instead of holding a traditional inauguration ceremony, throngs of supporters in Caracas swore an oath of loyalty in Chavez's absence. Many waved flags and carried photos of the president.
After several Latin American leaders were diagnosed with cancer, himself included, Chavez, ever the critic of Washington wondered aloud if the United States was behind it.