“Praying together, we’re going to achieve the miracle,” Maduro said.
The vice president, whom Chavez recently designated his preferred successor, also repeated his government’s condemnation of US President Barack Obama’s criticisms last week of “authoritarian policies” in Venezuela.
Maduro called Obama’s comments “unacceptable.”
Saturday night’s ceremony was held on the eighth anniversary of the creation of the leftist Bolivarian Alliance, or ALBA, bloc of nations, which includes Venezuela, Bolivia, Cuba and other nations.
Maduro read aloud a letter from Castro in which he said “the name of Hugo Chavez is admired and respected throughout the world.”
The former Cuban president was quoted as writing that “the doctors are fighting with optimism” for Chavez’s recovery.
Bolivian President Evo Morales, who attended the event in Caracas, told the television network Telesur that he had not yet been able to travel to Cuba, but that he hoped to meet with Chavez soon. He did not give details.