CARACAS, Venezuela — Hugo Chavez has suffered "new complications" following his cancer surgery in Cuba, his vice president said Sunday, describing the Venezuelan leader's condition as delicate.

Vice President Nicolas Maduro spoke with a solemn expression in a televised address from Havana, saying he had spoken with Chavez and that the president sent greetings to his homeland. Maduro did not give details about the complications, which he said came amid a respiratory infection.

"Several minutes ago we were with President Chavez. We greeted each other and he himself referred to these complications," Maduro said, reading from a prepared statement. The vice president was seated alongside Chavez's eldest daughter, Rosa, and son-in-law Jorge Arreaza, as well as Attorney General Cilia Flores.

Maduro's comments suggest an increasingly difficult fight for the ailing president. The Venezuelan leader has not been seen or heard from since undergoing his fourth cancer-related surgery Dec. 11, and government officials have said he might not return in time for his scheduled Jan. 10 inauguration for a new six-year term.

"The president gave us precise instructions so that, after finishing the visit, we would tell the (Venezuelan) people about his current health condition," Maduro said. "President Chavez's state of health continues to be delicate, with complications that are being attended to, in a process not without risks."

Maduro held up a copy of a newspaper confirming that his message was recorded on Sunday.

"Thanks to his physical and spiritual strength, Comandante Chavez is facing this difficult situation," Maduro said.

Maduro said he had met various times with Chavez's medical team and relatives. He said he would remain in Havana "for the coming hours" but didn't specify how long.

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

Before flying to Cuba, Maduro said that Energy Minister Hector Navarro would be in charge of government affairs in the meantime.

"The situation does not look good. The fact that Maduro himself would go to Cuba, leaving Hector Navarro in charge only seems understandable if Chavez's health is precarious," said David Smilde, a University of Georgia sociologist and analyst for the Washington Office on Latin America think tank.

Smilde said that Maduro probably made the trip "to be able to talk to Chavez himself and perhaps to talk to the Castros and other Cuban advisers about how to navigate the possibility of Chavez not being able to be sworn in on Jan. 10."

"Mentioning twice in his nationally televised speech that Chavez has suffered new complications only reinforces the appearance that the situation is serious," Smilde said.

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

Chavez said at the time that his cancer had come back despite previous surgeries, chemotherapy and radiation treatment. He has been fighting an undisclosed type of pelvic cancer since June 2011.

Medical experts say that it's 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.

Maduro's latest update differed markedly from last Monday, when he had said he received a phone call from the president and that Chavez was up and walking.

The vice president spoke on Sunday below a picture of 19th century independence hero Simon Bolivar, the inspiration of Chavez's leftist Bolivarian Revolution movement.

Maduro expressed faith that Chavez's "immense will to live and the care of the best medical specialists will help our president successfully fight this new battle." He concluded his message saying: "Long live Chavez."

Chavez has been in office since 1999 and was re-elected in October, three months after he had announced that his latest tests showed he was cancer-free.

Opposition politicians have criticized a lack of detailed information about Chavez's condition, and last week repeated their demands for a full medical report.

Information Minister Ernesto Villegas defended the government's handling of the situation, saying during a televised panel discussion on Sunday night that Chavez "has told the truth in his worst moments" throughout his presidency.

Villegas said a government-organized New Year's Eve concert in a downtown Caracas plaza had been canceled, and he urged Venezuelans to pray for Chavez.

Chavez's daughter Maria, who has been with the president since his surgery, said in a message on her Twitter account: "Thank you people of Venezuela. Thank you people of the world. You and your love have always been our greatest strength! God is with us! We love you!"

Allies of the president also responded on Twitter, repeating the phrase: "Chavez lives and will triumph."

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Ian James on Twitter: http://twitter.com/ianjamesap

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  • A man passes in front of a graffiti of Venezuelan President Hugo Chavez in Caracas, on January 2, 2013. Chavez is conscious and fully aware of how 'complex' his condition remains three weeks after difficult cancer surgery in Havana, the Venezuelan president's handpicked successor, Vice President Nicolas Maduro, said Tuesday. Maduro, who is returning to Caracas today on January 2, provided no specifics about Chavez's condition but defended the government's efforts to keep the public abreast of the president's health. Chavez underwent his fourth cancer-related surgery three weeks ago in Havana and has been bed-ridden ever since. (LEO RAMIREZ/AFP/Getty Images)

  • Supporters of Venezuela's President Hugo Chavez hold his picture during a vigil in Managua, Nicaragua, Sunday Dec. 9, 2012. (AP Photo/Esteban Felix)

  • Supporters of Venezuela's President Hugo Chavez gather during a vigil in Managua, Nicaragua, Sunday Dec. 9, 2012. (AP Photo/Esteban Felix)

  • A man wearing a T-shirt with a portrait of Venezuela's President Hugo Chavez prays during a vigil in Managua, Nicaragua, Sunday Dec. 9, 2012. (AP Photo/Esteban Felix)

  • A person holds up an image of Venezuela's President Hugo Chavez among religious images during a demonstration in support of him at the Simon Bolivar square in Caracas, Venezuela, Sunday Dec. 9, 2012. (AP Photo/Fernando Llano)

  • A woman holds a picture of Venezuela's President Hugo Chavez as supporters gather at Simon Bolivar square in Caracas,Venezuela, Sunday Dec. 9, 2012. (AP Photo/Fernando Llano)

  • A woman reacts during a demonstration in support of Venezuela's President Hugo Chavez at the Simon Bolivar square in Caracas, Venezuela, Sunday Dec. 9, 2012. (AP Photo/Fernando Llano)

  • A woman wears a pin with a picture of President Hugo Chavez that reads in Spanish 'love is repaid with love' as Venezuelan residents gather in support of Chavez in front of the embassy of Venezuela in Havana, Cuba, Sunday, Dec. 9, 2012. (AP Photo/Ramon Espinosa)

  • A woman reacts a supporters of Venezuela's President Hugo Chavez gather at the Simon Bolivar square in Caracas,Venezuela, Sunday Dec. 9, 2012. (AP Photo/Fernando Llano)

  • Women react as they gather at Simon Bolivar square in support of Venezuela's President Hugo Chavez in Caracas,Venezuela, Sunday Dec. 9, 2012. (AP Photo/Fernando Llano)

  • Venezuelan residents in Cuba gather in support of President Hugo Chavez in front of the embassy of Venezuela in Havana, Cuba, Sunday, Dec. 9, 2012. (AP Photo/Ramon Espinosa)

  • A Venezuelan resident in Cuba wearing a T-shirt with an image of Venezuela's President Hugo Chavez and carrying a Cuban flag participates in a demonstration in support of him in front of the embassy of Venezuela in Havana, Cuba, Sunday, Dec. 9, 2012. (AP Photo/Ramon Espinosa)

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  • A supporter of Venezuela's President Hugo Chavez shows his picture during a rally in Caracas on December 9, 2012. Chavez admitted a relapse of his cancer late Saturday and designated vice president Nicolas Maduro as his heir apparent in case 'something happened' to him. (JUAN BARRETO/AFP/Getty Images)

  • Supporters of Venezuela's President Hugo Chavez rally in Caracas on December 9, 2012. Chavez admitted a relapse of his cancer late Saturday and designated vice president Nicolas Maduro as his heir apparent in case 'something happened' to him. (JUAN BARRETO/AFP/Getty Images)

  • Supporters of Venezuela's President Hugo Chavez show a placard with his image during a rally in Caracas on December 9, 2012. Chavez admitted a relapse of his cancer late Saturday and designated vice president Nicolas Maduro as his heir apparent in case 'something happened' to him. (JUAN BARRETO/AFP/Getty Images)

  • Supporters of Venezuela's President Hugo Chavez show his picture during a rally in Caracas on December 9, 2012. Chavez admitted a relapse of his cancer late Saturday and designated vice president Nicolas Maduro as his heir apparent in case 'something happened' to him. (JUAN BARRETO/AFP/Getty Images)

  • A statuette depicting Venezuelan President Hugo Chavez is seen on display at a shop in Caracas on January 7, 2012. The church weighed in with four days to go before President Hugo Chavez, who is in Cuba recovering from cancer surgery, is supposed to be sworn in to a new six year term. (Leo Ramirez/Getty Images)