Chavez said he would start the treatment in Havana on Sunday in an attempt to ensure cancer cells do not reappear following last month's operation.

"We're going to give it everything we've got," Chavez said in a televised speech shortly before he left Caracas on Saturday. He said there is always a risk cancer cells might show up again, "and therefore there's a need to attack hard through chemotherapy."

Chavez was accompanied by one of his daughters, Rosa, who held his hand as they boarded the presidential jet. "It's not time to die. It's time to live," Chavez said.