The Venezuelan government says President, Hugo Chavez, is suffering from "complications" brought on by a "severe lung infection" which developed after surgery.
Mr Chavez, 58, had his fourth operation for cancer in Cuba on 11 December and then developed a respiratory infection.
Information Minister Ernesto Villegas says the infection is making breathing difficult for Mr Chavez and the Socialist leader has to continue with strict medical treatment.
He has warned the Venezuelan people about what he called a psychological war being waged in the media over Mr Chavez's health with the aim of destabilising the country.
The BBC reports the Venezuelan leader has not been seen nor heard in public since his operation three weeks ago.
He is due to be sworn in for another term in office in a week's time.