Venezuelan President Hugo Chavez has appeared at a rally in Caracas, telling supporters that his battle against cancer is one of the biggest fights of his life.

President Chavez wore his army uniform and red beret to the event, where he discussed his struggle with the disease. He raised the nation's flag over Plaza Bolivar, the square where the rally was held.

The crowd shouted: “Onward commander!” in support of the president, who underwent surgery last month in Cuba to remove a tumor from his pelvic region. Mr. Chavez has not said what kind of cancer he is battling.

On Wednesday, he announced that he may undergo chemotherapy or radiation in a future stage of his treatment. He said he has lost weight and is adopting a healthier lifestyle.

President Chavez, known for his hours-long speeches, has also curtailed some activities since his surgery. He said he has learned to delegate tasks to others.

Mr. Chavez returned to Venezuela from Cuba on July 4. He has assured Venezuelans that he intends to remain in control of the country, which is South America's biggest oil producer.

The 56-year-old president, an outspoken critic of the United States, took office in 1999.