Venezuela's president Hugo Chavez is suffering new complications after cancer surgery, prompting growing speculation about whether he has much longer to live.

Vice president Nicolas Maduro looked weary and spoke with a solemn expression as he announced in a televised address from Havana on Sunday that Mr Chavez now has a respiratory infection nearly three weeks after his operation. He described his condition as delicate.

The streets of Caracas were abuzz with talk of Mr Chavez's increasingly tough fight, while the news topped the front pages of the country's newspapers.

"He's history now," said Cesar Amaro, a street vendor selling newspapers and snacks at a kiosk in Caracas. He motioned to a newspaper showing side-by-side photos of Mr Maduro and National Assembly president Diosdado Cabello, and said politics will now turn to them.

He expected a new election soon to replace Mr Chavez. "For an illness like the one the president has, his days are numbered now," he said.

A government-organised New Year's Eve concert had been planned in a Caracas plaza featuring popular Venezuelan bands, but was cancelled due to Mr Chavez's condition. Information minister Ernesto Villegas urged Venezuelans to keep their president in their prayers.

Political analyst Ricardo Sucre said the outlook for Mr Chavez appears grim, saying Mr Maduro's body language during his televised appearance spoke volumes.

"Everything suggests Chavez's health situation hasn't evolved as hoped," he said. He said Mr Maduro probably remained in Havana to keep close watch on his condition.

"These hours should be key to having a more definitive prognosis of Chavez's health, and as a consequence make the corresponding political decisions according to the constitution," Mr Sucre said.

It seems increasingly unlikely that Mr Chavez will be able to be sworn in for a new term as scheduled on January 10.

He has not been seen or heard from since undergoing his fourth cancer-related surgery on December 11, and government officials have said he might not return in time for his inauguration for the six-year term.

If he dies or is unable to continue in office, the Venezuelan constitution says that a new election should be held within 30 days.

Before his operation Mr Chavez acknowledged he faced risks and designated Mr Maduro as his successor, telling supporters they should vote for the vice president if a new presidential election were necessary.

Mr Maduro, who arrived in Havana on Saturday for the sudden and unexpected trip, is the highest-ranking Venezuelan official to see Mr Chavez since the surgery in Cuba, where the president's mentor Fidel Castro has reportedly made regular visits to check on him.

Medical experts say that it is common for patients who have undergone major surgeries to suffer respiratory infections and that how a patient fares can vary widely from a quick recovery in a couple of days to a fight for life on a respirator.

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