(CNN) -- Venezuelan President Hugo Chavez, who is recovering from cancer surgery, has suffered "new complications," Vice President Nicolas Maduro said Sunday.
"President Chavez's state of health continues to be delicate, with complications that are being treated in a process that is not without risks," he said.
Maduro spoke in Havana, Cuba, where Chavez is undergoing treatment. He said he met with Chavez, who has not been seen in public or heard from for weeks.
"Thanks to his physical and spiritual strength, Comandante Chavez is confronting this difficult situation," Maduro said.
The Venezuelan president first announced he was battling cancer in June 2011.
Chavez, 58, has not disclosed what type of cancer he has, and the Venezuelan government has released few details about his illness, fueling widespread speculation about his health and political future.
Last year, Chavez had surgery to remove a cancerous tumor and has undergone further surgery and radiation in Cuba since. He returned to the island nation this month to undergo another surgery after publicly revealing that his cancer had returned.
He underwent a six-hour surgical procedure on December 11 that Maduro, in a televised address, declared a success.
A week after the president's surgery, the Venezuelan information minster said Chavez was battling a respiratory infection. Minister Ernesto Villegas said then that the infection was under control.
Recently both Villegas and Maduro have struck a somber tone when discussing the president's illness in contrast to previous government messages about his health. Villegas has suggested Chavez might not be not be back in Venezuela in time for his inauguration scheduled for next month.
Chavez addressed the delicate nature of his health before leaving Venezuela for Cuba. He said that if his health were to worsen, Maduro should replace him as president, making it the first time Chavez had spoken about a possible successor.