“Comandante Chavez has faced complications as a result of a severe lung infection," Information Minister Ernesto Villegas said in the latest official update on the president's condition, reported by Reuters.
"This infection has caused a breathing insufficiency that requires Comandante Chavez to comply strictly with medical treatment," the communique added, giving no further details.
Chavez is still in Cuba, and hasn't been seen or heard from since his Dec. 11 cancer surgery, and speculation has grown that his illness could be reaching its final stages.
The president's elder brother Adan and National Assembly President Diosdado Cabello joined a parade of visitors who saw Chavez in Havana this week, and then returned to Caracas on Thursday along with Vice President Nicolas Maduro, the president’s anointed successor, the Associated Press reported.
"In the past hours, we've been accompanying President Hugo Chavez and taking him the courage and strength of the Venezuelan people," Maduro said on television. Appearing next to Cabello visiting a coffee plant in Caracas, he said they had been with Chavez together with the president's brother, his son-in-law Jorge Arreaza, Oil Minister Rafael Ramirez and Attorney General Cilia Flores.
The political opposition is demanding more answers from the government, which has withheld details about the ailing leader’s health status.
Earlier, opposition leader Ramon Aveledo questioned the government’s limited account of Chavez’s illness over the past 18 months and called upon Maduro to provide more information.
"The official version hides more information than it gives," Aveledo said at a press conference, Reuters reported.
"The vice president himself has promised to tell the truth, whatever it is. Fine, he should tell it. He should tell the whole truth."
The Venezuelan government has said that Chavez remains in a “delicate” state after his fourth operation since it was first revealed that he had an unspecified form a cancer in 2011.
Maduro said earlier this week while visiting with Chavez in Havana that he had given him instructions to fully inform the public of his health status upon his return to Caracas.
"The president gave us precise instructions so that, after finishing the visit, we would tell the people about his current health condition,” Maduro said, according to the BBC.
There is widespread speculation that Chavez, who was re-elected to a third six-year term last October, may not return for his own inauguration on Jan. 10.
According to the Venezuelan constitution, if there is an “absolute absence” of the president prior to his or her inauguration, then new elections must be held within 30 days.
Before departing for Cuba for his operation, Chavez designated Maduro as his political heir, and he asked his supporters to stand behind him should he have to run in a snap election.
The political opposition would likely re-nominate Miranda state Governor Henrique Capriles Radonski, who ran against Chavez in last year’s elections, mounting the greatest challenge to the Venezuelan leader's 13-year presidency yet.
Capriles was re-elected to his governor’s seat last month, demonstrating his continued support despite losing to Chavez in the national election.
Given the state’s control over the majority of the Venezuelan media and the secrecy over Chavez’s health, it is unlikely that the political opposition will be able to mount any kind of serious challenge against the president so long as it is unclear whether or not Chavez will be able to continue.
Venezuelan bonds rallied to five-year highs earlier on Thursday on rumors that Chavez's health had taken a turn for the worse, Reuters reported. Foreign investors hope for a more business-friendly government in Venezuela if he goes, and its assets have rallied in recent months on news of his illness.
Maduro told workers at the nationalized Fama de America coffee factory in Caracas Thursday that there was no "transition" taking place in the country.
"The only transition in Venezuela is the transition to socialism," he said in comments carried live by state television.
"It began six years ago, ordered by Comandante Hugo Chavez as chief and president, elected, re-elected and ratified, much as it pains the bourgeois hucksters and the right, who have done so much damage to our fatherland."