BOGOTA -- Venezuelan President Hugo Chávez was in the midst of the most “difficult test of his life” as he underwent surgery in Cuba for recurring cancer, Ecuadoran President Rafael Correa said Tuesday.

During a meeting with his Colombian counterpart in the Ecuadoran border town of Tulcán, Correa said he found Chávez in good spirits when he visited him in Havana on Monday, but he said the surgical procedure he is undergoing is “delicate.”

“Our hearts and solidarity are with him,” Correa said, according to the state-run El Cuidadano newspaper. “He’s a historic president and hopefully he will recover fully.”

Chávez traveled from Venezuela to Cuba early Monday to undergo a fourth-round of surgery to treat an undisclosed form of cancer that he’s been battling since at least June 2011.

The Venezuelan government has released few details about his health, but announced Tuesday afternoon that Chávez was in surgery.

“The medical team has said it’s optimistic about the success of the operation,” Minister of Communications Ernesto Villegas said in a brief televised statement. “We call on the people of Venezuela to keep praying and to transmit their purest feelings of love to Commander Chávez.”

On Saturday, Chávez told the nation that his doctors had found “malignant cells” near the site where he had a tumor removed from his pelvis last year. This is the second time he has acknowledged suffering a relapse. The government has never said what type of cancer the president has or what organs are being affected.

The health scare has cast doubts on whether the 58-year-old leader will be fit to assume a new six-year term on Jan. 10. Before leaving for Cuba, Chávez said that Vice President Nicolás Maduro would take the helm of the oil-rich nation if he was “incapacitated” and oversee new presidential elections.