Venezuelan President Hugo Chavez delegated some of his powers to his vice president and finance minister Saturday, hours before traveling back to Cuba for a “second phase” of cancer treatment.

Mr. Chavez resisted calls from the opposition to temporarily hand over the presidency to Vice President Elias Jaua during his absence. But shortly after the national assembly approved his trip, the Venezuelan leader gave Jaua and Finance Minister Jorge Giordani extra responsibilities that include budgetary matters.

Mr. Chavez told reporters Friday the new phase of treatment will include chemotherapy. He returned from Cuba where he had surgery to remove a cancerous tumor on July 4, one day before Venezuela celebrated the 200th anniversary of its independence from Spain. The Venezuelan leader did not indicate the type of cancer he had, and questions remain about how sick he is. Prior to that surgery, Mr. Chavez underwent an operation in Cuba for what officials said was an abscess in his pelvic area.

The president has assured Venezuelans that he intends to remain in control of the country, South America's biggest oil producer. During a rally in Caracas Thursday, Mr. Chavez told supporters his battle against cancer is one of the biggest fights of his life.

The 56-year-old president, an outspoken critic of the United States, has ruled Venezuela since 1999.