* Complications linked to respiratory infection
* Venezuelan president still in delicate state
* Events in oil-rich country would have impact abroad
Venezuelan President Hugo Chavez is suffering further complications linked to a respiratory infection that hit him after his fourth cancer operation in Cuba, his vice president said in a somber broadcast on Sunday.
Vice President Nicolas Maduro flew to Cuba to visit Chavez in the hospital as supporters' fears grow for the ailing 58-year-old socialist leader, who has not been seen in public nor heard from in three weeks.
Chavez had already suffered unexpected bleeding caused by the six-hour operation on Dec. 11 for an undisclosed form of cancer in his pelvic area, and officials say doctors then had to fight a respiratory infection.
"Just a few minutes ago we were with President Chavez. He greeted us and he himself talked about these complications," Maduro said in the broadcast, adding that the third set of complications arose because of the respiratory infection.
"Thanks to his physical and spiritual strength, Comandante Chavez is confronting this difficult situation."
Maduro, flanked by his wife Attorney-General Cilia Flores, Chavez's daughter Rosa Virginia and her husband, Science Minister Jorge Arreaza, said he would remain in Havana while Chavez's condition evolved.
Chavez's resignation for health reasons, or his death, would upend politics in the OPEC nation where his personalized brand of oil-financed socialism has made him a hero to the poor but a pariah to critics who call him a dictator.
The president's allies have been openly discussing the possibility that he may not be able to return to swear in for his third six-year term on the constitutionally mandated date of Jan. 10.
Opposition leaders say a postponement would be another signal Chavez is not in a fit state to govern and that new elections should be called to choose his replacement.
They believe they have a better shot against Maduro, who was named earlier this month by Chavez as his heir apparent, than against the charismatic president who for 14 years has been nearly invincible at the ballot box.
Any constitutional dispute over succession could lead to a messy transition toward a post-Chavez era in the country with the biggest oil reserves in the world.
Maduro has become the face of the government in Chavez's absence, imitating the president's bombastic style and sharp criticism of the United States and its "imperialist" policies.