BOGOTA -- Venezuelan President Hugo Chávez will travel to Cuba Friday to undergo surgery to remove a lesion that is suspected of being malignant.

Talking to his cabinet on live TV Thursday, Chávez, 57, said he would likely undergo the surgery on Monday or Tuesday.

He also warned his followers to ignore the rumors about his health while he is on the island.

“Unfortunately, there are laboratories that invent these campaigns, so we have to be alert,” he said. “I’ve told [Vice President Elias Jaua] to keep me informed every day about what is being said, so nothing catches us by surprise. We cannot allow lies or half truths.”

On Thursday, the National Assembly granted Chávez permission to leave the country – a requirement when the head of state will be gone for more than five days. However, Chávez is not delegating power.

The president will “stay at the helm of the government like he did last time,” Vice President Jaua told state-run television.

Last June, doctors in Cuba removed a malignant tumor from Chávez abdominal region. The president has never said what type of cancer it was or what organ was being affected, but the resulting treatment left him bald and bloated.

Facing a tight Oct. 7 reelection campaign, Chávez had appeared to be on the mend, and was stepping up public appearances and resuming hours-long speeches.

Earlier this week, amid rumors that his health was failing, Chávez admitted that doctors had found a 2-cm lesion on the site where his previous tumor was removed. On Tuesday, he said that due to its location it was possibly malignant, but he denied reports that the cancer had spread.

The coalition of opposition parties has asked Chávez to be more forthcoming with his health, saying it was the government’s secrecy that was fueling the rumors.

Chávez has warned supporters that he may be out of the public eye for “weeks,” but has vowed to return to Venezuela as soon as possible to resume the presidential campaign.

“Chávez is going to overcome this, the nation will overcome this,” Jaua said, “and we are going to have a great victory October 7th, with Chávez as our candidate.”