Venezuela's vice-president says that President Hugo Chavez could be sworn in by the Supreme Court later on if he's not able to take the oath of office next week before lawmakers.

Vice-President Nicolas Maduro made the comment in a televised interview on Friday night.

Maduro says Chavez, as a re-elected president, remains in office beyond the swearing-in date stipulated in the constitution, and could be sworn in if necessary before the Supreme Court at a date to be determined.

• Hugo Chavez suffers 'respiratory deficiency' after surgery

He dismissed the argument by some opposition leaders that new elections must be called if Chavez doesn't take office as scheduled on Thursday.

The brewing disagreements over how to handle a possible transition of power also could be aired at a Saturday session of Venezuelan lawmakers. The session could shed light on what steps may be taken if President Hugo Chavez is too sick to be sworn in for a new term next week.

Legislators will choose a president, two vice-presidents and other leaders of the National Assembly, which is controlled by a pro-Chavez majority. Whoever is elected National Assembly president could end up being the interim president of Venezuela if Chavez is unable to be inaugurated on Jan. 10 as scheduled.

Severe lung infection, respiratory deficiency

The government revealed this week that Chavez is fighting a severe lung infection and receiving treatment for "respiratory deficiency" more than three weeks after undergoing cancer surgery in Cuba. The announcement suggests a deepening crisis for the 58-year-old president and has fed speculation that he likely is not well enough to travel to Caracas for the inauguration.

'If the opposition thinks it will find a space in the National Assembly to conspire against the people, it's mistaken.'—Tweet from National Assembly President Diosdado Cabello

National Assembly President Diosdado Cabello called on Chavez backers to show up for the legislative session and demonstrate their support.

"This National Assembly is revolutionary and socialist. It will remain beside the people and our commander," Cabello said in one of several messages on his Twitter account. "If the opposition thinks it will find a space in the National Assembly to conspire against the people, it's mistaken once again. It will be defeated."

Opposition leaders have demanded that the government provide more specific information about Chavez's condition, and say a new election should be held within 30 days if the president doesn't return to Venezuela by inauguration day.

Some Chavez allies say the inauguration date is not a hard deadline, and argue that the president should be given more time to recover from his surgery if necessary.

Chavez may be using ventilator

Chavez hasn't spoken publicly or been seen since his Dec. 11 operation in Cuba. In a Thursday night update, the government for the first time described the president's respiratory infection as "severe," the strongest confirmation yet that Chavez is having serious trouble breathing after days of rumours about his condition worsening.

"Chavez has faced complications as a result of a severe respiratory infection. This infection has led to respiratory deficiency that requires Commander Chavez to remain in strict compliance with his medical treatment," Information Minister Ernesto Villegas said Thursday night, reading a statement on television.

The government's characterization raised the possibility that Chavez might be breathing with the assistance of a machine. But the government did not address that question and didn't give details of the president's treatment.

Venezuela's President Hugo Chavez has said the country's Vice-President Nicolas Maduro should be his party's candidate to replace him in a re-election, if one is necessary. (Miraflores Palace/Handout/Reuters)

Independent medical experts consulted by The Associated Press said the government's account indicated a potentially dangerous turn in Chavez's condition, but said it's unclear whether he is attached to a ventilator.

"It appears he has a very severe pneumonia that he suffered after a respiratory failure. It is not very specific," said Dr. Alejandro Rios-Ramirez, a pulmonary specialist in Puerto Vallarta, Mexico.

Dr. Gustavo Medrano, a lung specialist at the Centro Medico hospital in Caracas, said he has seen similar cases in cancer patients who have undergone surgery, and "in general it's very bad, above all after a surgery like the one they performed on him."

"I don't know the magnitude of the infection he has, how much of his lungs have been compromised, how much other organs are being affected. That's not clear," Medrano said.

"What's most likely is that he's on mechanical ventilation," Medrano added. However, he said, while respiratory deficiency means there is an abnormally low concentration of oxygen in the blood, depending on the severity it can be treated in various ways.

4th cancer-related surgery since June 2011

The government expressed confidence in Chavez's medical team and condemned what it called a "campaign of psychological warfare" in the international media regarding the president's condition. Officials have urged Venezuelans not to heed rumours about Chavez's condition.

Opposition leaders have blamed vague information coming from the government for the rumours, and demanded a full medical report.

A religious altar with images of Venezuela's President Hugo Chavez, who has not been heard from since undergoing a cancer-related operation in Cuba. (Carlos Garcia Rawlins/Reuters)

Chavez has undergone four cancer-related surgeries since June 2011 for an undisclosed type of pelvic cancer. He also has undergone chemotherapy and radiation treatment.

He was re-elected in October to another six-year term, and two months later announced that the cancer had returned. Chavez said before the operation that if his illness prevented him from remaining president, Vice-President Maduro should be his party's candidate to replace him in a new election.

This week, Cabello and the president's elder brother Adan joined a parade of visitors who saw Chavez in Havana, and then returned to Caracas on Thursday along with Maduro.

The Venezuelan Constitution says the presidential oath should be taken Jan. 10 before the National Assembly. Government officials have raised the possibility that Chavez might not be well enough to do that, without saying what will happen if he can't. The constitution also says that if the president is unable to be sworn in before the National Assembly, he may take the oath office before the Supreme Court.

The constitution says that if a president or president-elect dies or is declared unable to continue in office, presidential powers should be held temporarily by the president of the National Assembly and a new election should be held within 30 days.