Venezuelan President Hugo Chavez was in surgery Tuesday in Havana to treat a return of his cancer, Ecuador's President Rafael Correa said, after visiting his close ally in Cuba.

Chavez is being subjected "at this instant to a very delicate operation," Correa said in opening a meeting with Colombian President Juan Manuel Santos in the border city of Tulcan, 150 kilometers (90 miles) north of Quito.

Earlier Chaves was said to be in good spirits. "He gives us all strength," Correa said on his Twitter account

The Ecuadoran president, a close Chavez ally and possible successor to lead the Latin American left, rushed to his colleague's side Monday after the Venezuelan president flew to Havana for his fourth round of surgery.

Chavez, who won reelection in October, had claimed he was cancer free but stunned his countrymen Saturday when he revealed that the disease had returned and designated a successor, Vice President Nicolas Maduro.

Correa said he visited with Chavez and Cuban President Raul Castro and Fidel Castro during the day long stay in Havana.

With Cuba's backing, Chavez has taken the lead in forming a bloc of leftist Latin American governments that vehemently opposes the United States and has friendly relations with US adversaries like Iran.

Members of the group include Ecuador, Nicaragua, Bolivia, Venezuela and Cuba.