Venezuela's government has said President Hugo Chavez is being treated for "respiratory deficiency" after complications from a severe lung infection.
Information Minister Ernesto Villegas provided the update on Mr Chavez's condition days after officials admitted the left-wing leader's condition was "delicate".
He read from a statement saying that the politician's lung infection had led to "respiratory deficiency" and required strict compliance with his medical treatment.
The government expressed confidence in Mr Chavez's medical team and condemned what it called a " campaign of psychological warfare" in international media surrounding the president's condition.
Dr Michael Pishvaian, an oncologist at Georgetown University's Lombardi Cancer Center in Washington, said such respiratory infections range from "a mild infection requiring antibiotics and supplemental oxygen to life threatening respiratory complications".
"It could be a very ominous sign," he said.
Officials have urged Venezuelans not to heed rumours about their cancer-stricken president's health.
The 58-year-old has not been seen or heard from since an operation in Cuba on December 11.
Venezuela's opposition has demanded more specific information from the government about his health.
Mr Chavez has undergone four cancer-related operations since June 2011 for an undisclosed type of pelvic cancer.
He has also had chemotherapy and radiation treatment.
He was re-elected in October to another six year term, announcing two months later that the cancer had come back.
Mr Chavez is due to be sworn in on January 10 but his closest allies still aren't saying what they plan to do if the ailing leader is unable to return from a Cuban hospital to take the oath of office.