CARACAS (Reuters) - Hugo Chavez is upbeat about recovering from cancer and confident in his medical team, his No. 2 said on Tuesday in the latest message from the Venezuelan leader's sickbed in Cuba.

"He told us with great strength: 'I am very optimistic, I trust completely in the treatments I am undergoing, I will beat this again. I'm holding onto Christ and life,'" Vice President Nicolas Maduro said of Chavez's words to him on a recent visit.

In power for the past 14 years, the South American OPEC member's socialist leader has not been seen or heard from in public since December 11 surgery in Havana. That was his fourth for a cancer first detected in the pelvic area in June 2011.

Opposition leaders say if Chavez, 58, is well enough to talk to ministers, then he should address the nation and tell Venezuelans exactly what condition he is in.

Despite complications including a lung infection after the operation, officials have been more optimistic about Chavez's state in the past two weeks, suggesting he was over the worst of the surgery repercussions and may come home soon.

They acknowledge, however, that Chavez's health remains delicate, and many Venezuelans believe his active rule is probably over, with a homecoming possibly aimed at smoothing a transition of power.

Maduro, 50, is Chavez's preferred political heir.

"Our commander-president is in a tough and complex battle, but with a phenomenal spirit," Maduro said in a speech in Sabaneta, the rural village where Chavez was born.

Maduro visited Chavez in Cuba before a weekend summit in Chile.

The vice president accused opposition supporters of stirring up trouble during Chavez's absence, delighting in his health problems and even plotting against senior government officials.

Even within "Chavista" circles, Maduro said, there are some murmurings of dissent that needed to be quashed.

"Though they are few, they are sometimes going around stirring up the waters to make themselves leaders or bosses of the revolution," he said. "We will give names in due course if necessary. ... We urge the people to put them in their place. They need to be clear who the leader and boss is."

(Reporting by Andrew Cawthorne, Diego Ore and Deisy Buitrago; Editing by Will Dunham)