Updated 3:15 a.m. EST
CARACAS, Venezuela A new and severe respiratory infection has cancer-stricken President Hugo Chavez in a "very delicate" state, and his breathing has deteriorated, the Venezuelan government announced late Monday.
Communications Minister Ernesto Villegas read a brief statement on national television saying Chavez's "worsening respiratory function" was related to a weakening of his immune system.
He said the charismatic socialist leader had "a new and severe infection." The state news agency identified it as a respiratory infection.
Villegas said Chavez had been undergoing "chemotherapy of strong impact, among other treatments."
He said Chavez's condition continues to be very delicate and that he was "standing by Christ and life conscious of the difficulties he faces."
"As Chavez' medical condition has worsened, the debate about what happens next in Venezuela has intensified, says CBS News' Pamela Falk. "Venezuela became deeply divided during Chavez's rule, and the political debate between Venezuelan Vice President Nicolas Maduro (Chavez' selected heir apparent) and opposition leader Henrique Capriles appears to define the debate that will play out if Chavez were to resign or die. It is the choice of a new way or the status quo."
In his statement, Villegas lashed out at "the corrupt Venezuelan right" for what he called a psychological war seeking "scenarios of violence" to encourage "foreign intervention in Venezuela."
Upon Chavez's death, the opposition would contest the government's candidate in a snap election, and the campaigning has already begun although undeclared.
Chavez has governed Venezuela, gradually placing all state institutions under his personal control, for more than 14 years.
Opposition lawmaker Julio Borges condemned Villegas' statement via Twitter as an inappropriate use of a medical bulletin for political reasons: "I lament such a poverty of humanity."
There has been speculation that Chavez's cancer has spread to his lungs and can't be halted.
An oncologist not involved in Chavez's treatment, which has been conducted in secrecy, told The Associated Press that he viewed Villegas' statement as recognition that Chavez's condition is "truly precarious." He called into question the veracity of Villegas' statement that Chavez had been under chemotherapy, saying patients in such a delicate state simply are not put on chemotherapy.
Vice President Nicolas Maduro, who Chavez has said should succeed him as president, first announced last week that the president had begun receiving chemotherapy around the end of January.
Doctors have said that such therapy was not necessarily to try to beat Chavez's cancer into remission but could have been palliative, to extend Chavez's life and ease his suffering.
The 58-year-old Chavez was flown home to Venezuela on Feb. 18, a little more than two months after undergoing his fourth surgery in Cuba for an unspecified cancer in the pelvic region.
He suffered a severe respiratory infection in Cuba in the last days of 2012 that nearly killed him, Vice President Nicolas Maduro said last week.
A tracheal tube was inserted then and government officials have said his breathing remained labored.
The cancer was first diagnosed in June 2011, and Chavez has undergone radiation treatment and chemotherapy after operations.
He has not been seen nor heard of - other than proof-of-life photos released on Feb. 15 - since he flew to Cuba for his last surgery, which was performed on Dec. 11.