Venezuelan President Hugo Chavez has entered the phase of "complementary treatment" following his cancer surgery in December in Cuba, Vice President Nicolas Maduro announced.

Maduro made the statement after his return from Havana, where he was able to see the recovering Chavez and had found him "in his best moment."

"The president has entered the phase of complementary treatment in order to combat his illness," said Maduro upon his return.

He promised a detailed update about the current condition of the Venezuelan leader on Saturday.

He added, however, that the president was "optimistic and has a lot of faith in what we are doing" and was "clinging to Christ and life."

The firebrand leftist leader has not been seen for more than a month since undergoing his latest round of cancer surgery in Havana. Government officials have repeatedly said in recent days that his condition is improving.

Venezuelan Foreign Minister Elias Jaua said Thursday Chavez was making progress in his recovery from cancer surgery, but faced a tough battle ahead.

Chavez, who had surgery on December 11, is a former paratrooper who first came to power in the oil-rich South American country in 1999 and won another six-year term in October, despite questions about his health.

Throughout his illness, first detected in June 2011, Chavez has refused to relinquish the powers of the presidency, even when leaving for Cuba last month.

He suffered complications following his latest surgery, including a severe lung infection.

Chavez was too sick to attend his January 10 inauguration, prompting the government to delay the swearing-in indefinitely under an interpretation of the constitution that was heavily criticized by the opposition.

The Chavez-controlled National Assembly and Supreme Court both approved the arrangement, which keeps his administration in place under Maduro until the president can take the oath of office for his fourth term.