A new and severe respiratory infection has hit cancer-stricken Venezuelan President Hugo Chavez and his breathing has deteriorated.
Communications Minister Ernesto Villegas read a brief statement on national television late on Monday saying Mr Chavez's "worsening respiratory function" was related to a weakening of his immune system.
He said the socialist leader had "a new and severe infection". The state news agency identified it as a respiratory infection.
Mr Villegas said Mr Chavez had been undergoing "chemotherapy of strong impact, among other treatments". He said Mr Chavez's condition continues to be very delicate and that he was "standing by Christ and life conscious of the difficulties he faces".
In the statement, Mr 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 Mr Chavez's death, the opposition would fight the government's candidate in a snap election, and the campaigning has already begun although undeclared.
Mr Chavez has governed Venezuela, gradually placing all state institutions under his personal control, for more than 14 years.
Opposition politician Julio Borges condemned Villegas' statement via Twitter as an inappropriate use of a medical bulletin for political reasons.
There has been speculation that Mr Chavez's cancer has spread to his lungs and cannot be halted.
Vice President Nicolas Maduro, who Mr 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 Mr Chavez's cancer into remission but could have been palliative, to extend his life and ease his suffering.