(CNN) -- Venezuelan President Hugo Chavez is fighting a new infection, and his breathing problems have worsened, Information Minister Ernesto Villegas said late Monday.
"There is a worsening of the respiratory function, related to the state of his depressed immune system," Villegas said, reading an official statement on state-run VTV.
He reported Chavez is battling a new and "severe" infection, stressing that his overall condition remains "very delicate." Chavez is undergoing chemotherapy and other treatments, he said.
"The president continues to hold fast to Christ and to life, aware of the difficulties he's facing," Villegas said.
Chavez, 58, first announced he had cancer in 2011. He spent more than two months in treatment in Cuba recently, returning to Venezuela two weeks ago.
The government has never specified what kind of cancer Chavez has.
Vice President Nicolas Maduro said Friday that Chavez is "fighting for his life." The president began chemotherapy after his fourth cancer surgery in Cuba in December, and he is continuing the "intense" treatment at a military hospital in Caracas, according to Maduro.
Since Chavez underwent surgery on December 11, government accounts about his health have been vague.
After previous procedures, Chavez called state television to offer upbeat, if vague, reports on his condition. There have been no such calls in recent weeks, and he has not been seen in public.
The last glimpse Venezuelans had of their leader was last month when the government released a series of photographs that showed a smiling Chavez -- his face bloated -- lying on a blue pillow, flanked by his two daughters.
The president's allies maintain he is continuing to run the country, while critics say Venezuela is in limbo without a leader, and are demanding more details on his health.
CNN's Mariano Castillo contributed to this report.