Venezuela's top court has endorsed the postponement of the inauguration of Hugo Chavez this week and ruled that the cancer-stricken president and his deputy could continue in their roles.

Critics had argued that the 58-year-old's absence from his own swearing-in ceremony due to take place later today meant a caretaker president must be appointed.

Mr Chavez has not been seen in public or heard from in almost a month following surgery in Cuba.

Supreme Court Chief Judge Luisa Morales told a news conference: "Right now we cannot say when, how or where the President will be sworn in," 

"As president re-elect there is no interruption of performance of duties ... The inauguration can be carried out at a later date before the Supreme Court."

The decision opens the door in theory for Mr Chavez to remain in office for weeks or months more from a Cuban hospital bed, even though there is no evidence he is even conscious.

It leaves the South American country in the hands of Vice President Nicolas Maduro, as de-facto leader of the government.

The opposition said that is a brazen violation of the constitution.

It said that Mr Maduro should leave office today, when the current presidential term had been due to expire.

The opposition said National Assembly boss Diosdado Cabello, another powerful Chavez ally, should take over the running of the country while new elections would be organised within 30 days.

Mr Maduro would be the ruling Socialist Party's candidate.

Government leaders insist Mr Chavez, 58, is fulfilling his duties as head of state, even though official medical bulletins say he suffered complications after the surgery, including a severe lung infection and has had trouble breathing.