Venezuelan president Hugo Chavez will miss Thursday's scheduled swearing-in ceremony for his fourth term due to health problems, the country's government announces.

Hugo Chavez (pic: Reuters)

Mr Chavez is in hospital in Cuba after cancer surgery, and has suffered complications caused by a lung infection.

His absence will add to fears that he will never be well enough to resume office.

Chavez has not been heard from since undergoing his fourth cancer surgery in Cuba on 11 December, and officials have described his condition as "delicate."

Venezuela's opposition has called for the Supreme Court to rule on what should be done if Mr Chavez is absent.

Its leader, Henrico Capriles, says that if Mr Chavez is not sworn in, then according to the constitution the National Assembly speaker should act as caretaker president until new elections are held within 30 days.

The government insists that the inauguration is a mere formality for an incumbent leader.

Mr Chavez has been president since 1999.