* President had not been seen since Dec. 11 cancer surgery
* Government says he is breathing through a tracheal tube (Updates with quotes from Maduro and Cabello, details)
By Daniel Wallis and Marianna Parraga
CARACAS, Feb 15 (Reuters) - Venezuela published the first photos of cancer-stricken Hugo Chavez since his surgery in Havana more than two months ago, and said the socialist president was breathing through a tracheal tube and struggling to speak.
The pictures showed the 58-year-old, his face looking swollen but smiling, lying down in a hospital bed and flanked by his two daughters. In one, they were reading Thursday's edition of the Cuban state newspaper Granma.
The photos were shown on Friday by Chavez's son-in-law, Science Minister Jorge Arreaza, who has been traveling between Havana and Caracas to be at his bedside.
He said that Chavez - whose political identity is built around long-winded speeches, meandering talk shows and casual chatter with supporters - was having trouble talking.
"He doesn't have his usual voice," Arreaza told Venezuelan state television. "He has difficulty communicating verbally, but he makes himself understood. He communicates his decisions perfectly. He writes them down."
Chavez has not appeared in public, and has still not been heard from, since the operation on Dec. 11, his fourth surgery for a cancer in his pelvic region first diagnosed in mid-2011.
Neither the pictures nor the new details on his condition offer solid clues as to when he might be able to return home, or whether the disease will force him to step down.
Allies appear content to let Chavez continue governing silently from Havana indefinitely, and bristle when asked about how the long the unusual arrangement could last.
The former soldier has never disclosed what type of cancer he has been treated for, and in his absence critics have accused government officials of secrecy over his condition.
"A few days ago the liars said they were speaking with the president. Now they say he can't talk!" opposition leader Henrique Capriles said on Twitter. "They are playing around with their own people."
Chavez was re-elected for a new six-year term in October after appearing to have staged a remarkable recovery from the disease following three earlier operations and weeks of grueling chemotherapy and radiation sessions.
But he soon had to fly back to Cuba for more medical tests, then another round of complex surgery. He was too ill to return to Venezuela for his inauguration ceremony last month.
The government, which said the new photos were taken on Thursday night, added that he has respiratory problems.
"The post-operative respiratory infection was controlled, but there is still some insufficiency," it said in its latest official communique on the president's health.
"Under these circumstances, which are being treated, the commander is currently breathing through a tracheal tube."
'CHAVEZ LIVES AND SMILES!'
On Wednesday, Vice President Nicolas Maduro - Chavez's preferred successor - said his boss was undergoing "tough" and "complex" alternative treatments, but did not give details.
If Chavez died or had to step aside, the authorities would have to call a new vote within 30 days. That would likely pit Maduro against Capriles, the 40-year-old governor of Miranda state who lost to Chavez in last October's election.
Maduro has sought to copy Chavez's fierce rhetoric against his rivals, and on Friday he again took aim at Capriles.
"This loser's heart is so bad it makes it mad that President Chavez is well," the vice president said in televised comments.
Amid so much uncertainty, some in the opposition believe Cuba's Fidel and Raul Castro - close Chavez allies - could be pulling strings behind the scenes.
About 20 student protesters chained themselves together in a street near the Cuban embassy in Caracas on Thursday, demanding details on his condition. Maduro warned that Capriles and others in the "neo-fascist" opposition would be held responsible for any violence there.
For many critics Maduro's words were an echo of Chavez's typically combative style, harsh criticism of Washington and radical leftist policies, including widespread nationalizations, which they say have crippled the OPEC nation's economy.
But the president's singular brand of oil-fueled welfare spending and folksy charisma has also won him a near-religious following among many poor Venezuelans. Supporters reacted to the new images with joy, tweeting: "Chavez lives and smiles!"
"Chavez's smile is the smile of the children, of the mothers, the young, the soldiers and the men. It's the smile of the fatherland," said Diosdado Cabello, the powerful head of the National Assembly and an ex-army buddy of the president.
The normally loquacious leader's silence since the surgery has convinced many Venezuelans that his extraordinary 14 years in power could be coming to an end.
His son-in-law Arreaza, however, described a light-hearted mood around the president, who he said enjoyed receiving visitors in his hospital room where he listened to music from his rural boyhood home in Venezuela's central plains.
"It's a party," Arreaza told state TV. (Additional reporting by Mario Naranjo; Editing by Brian Ellsworth and Vicki Allen)