CARACAS (AP) ― President Hugo Chavez announced Tuesday that doctors in Cuba found a new lesion in the same place where he had a tumor removed last year and said he will require surgery.

“It is a small lesion of about 2 centimeters in diameter, very clearly visible,’’ Chavez told state television.

The announcement thrust Venezuelan politics into new uncertainty because the socialist leader is seeking re-election this year, hoping to extend his more than 13 years in power with a new six-year term.

He did not say when or where he would undergo the surgery, other than “in the coming days.’’ He said he would meet with his inner circle to decide and expected to provide more details after a Wednesday Cabinet meeting.

Chavez, 57, said it should be less complicated than what he underwent in Cuba last June, when doctors removed a cancerous tumor from his pelvic region.

From July to September, Chavez received four rounds of chemotherapy, both in Cuba and in Venezuela, and he subsequently said tests showed he was cancer-free.

On Tuesday, Chavez denied rumors that the cancer had spread aggressively even as he said doctors do not know whether the new growth is malignant or not.

“I completely deny what’s going around that I have metastasis in the liver or I don’t know where, that the cancer has spread all over my body and that I’m already dying,” he said.

He has never specified the cancer’s exact nature or location, and opposition politicians and critics have repeatedly accused Chavez of a lack of transparency.

Analyst Cynthia Arnson of the Woodrow Wilson International Center in Washington said Tuesday’s announcement seriously complicates Chavez’s prospects for re-election on Oct. 7.

“It’s now clear that Chavez’s cancer is far from cured. Chavez’s illness _ his ability to campaign as well as to govern _ is a major factor in the race. It erodes the aura of invincibility as well as inevitability that Chavez has always tried to create,” she said.

The governing party will also be vexed as it lacks an alternative with Chavez’s charisma and popular following, Arnson said. She predicted Tuesday’s news will make “a tight race even tighter” against opposition candidate Henrique Capriles, a 39-year-old state governor.

Speaking from his home state of Barinas, Chavez said he decided to go public with the information about his need for surgery “because there are so many rumors, including rumors has been spreading.”

Chavez, whose approval ratings have topped 50 percent in recent polls, had been out of public sight since Friday, and his government’s handling of unconfirmed reports that he spent the weekend in Cuba for medical tests turned out to be ham-fisted. On Monday, repeated attempts by The Associated Press to confirm the reports went unanswered, and Communications Minister Andres Izarra vehemently denied them online.

“Regarding the rumors, dirty war from the gutter,’’ Izarra tweeted.

Also Monday, an employee of the Venezuela Embassy in Havana said there was no indication that Chavez had gone to Cuba or planned to do so. The person did say that some family members of the president were in Cuba but had already left. The employee spoke on condition of anonymity, lacking authorization to discuss the matter publicly.

Security was noticeably tight Friday and Saturday at the Cimeq hospital in Havana, considered the country’s best and believed to be where Chavez, Fidel Castro and other powerful people have sought treatment.

In recent weeks, Chavez has recovered the hair he shaved off during chemotherapy and he has appeared vigorous, albeit puffy around the face and neck. He had returned to a full schedule of activities including marathon television appearances. It was not immediately clear how his new surgery and recuperation from it might affect his routine and campaigning.

“I am in good physical shape to confront this new battle,” Chavez said Tuesday.

But he also waxed on his own mortality:

“It’s a life that I ask God to extend as long as he pleases only, if only, to be able to better serve each and every day the Venezuelan people.’’

Doctors consulted by The Associated Press said Chavez simply has not provided enough information to assess his prognosis.

Dr. Javier Cebrian, a colorectal specialist and chief surgeon at University Hospital in Caracas, said news that the lesion was in the very place the initial tumor was removed was not a good sign.

“A local recurrence is a bad symptom because it means the illness is growing again,’’ he said.

“It’s an ominous sign,” said Dr. Michael Pishvaian, a Georgetown University oncologist. He said doctors often use the term lesion to refer to a new tumor, which appears to fit Chavez’s description.

He said such a reappearance, particularly when a patient has undergone surgery then chemotherapy, suggests cancerous cells have resisted the treatments.

A leading Colombian oncologist, Dr. Carlos Castro, said conflicting information provided by the Venezuelan president himself made any assessment extremely difficult.

“He says he doesn’t have metastasis. But a week ago he said he hadn’t had a recurrence. And now he says that he needs to be operated on again,’’ Castro told the AP in Bogota, Colombia.

Castro said Chavez could be expected to need radiation therapy if another tumor is removed and that typically means a minimum of 10 daily sessions, which means Chavez would need to name a temporary replacement while undergoing treatment.

Capriles’ campaign coordinator, Armando Briquet, said he and his team wish Chavez “a complete recovery” and “a long life although we have always been critical about the lack of real information about the president’s health.’’

“We don’t know exactly the extent, or what he has, or where he has it,” Briquet added.

Capriles claims Chavez has exploited his lengthy rule to balance the scales against a fair election, taking advantage of government money and slanted coverage in state media.

He is a strident critic of Chavez’s expropriations of hundreds of businesses, apartment buildings and farms over the past decade.

The government’s generous spending has made Chavez a hero to many of his supporters, which make up a large segment of Venezuela’s poor.

Opponents say Chavez has done nothing to combat Venezuela’s rampant violent crime and blame him for 26 percent inflation. His opponents also criticize the former paratroop commander for his strident anti-U.S. rhetoric and defense of Iran and its nuclear program.

The U.S. Embassy in Caracas has been without an ambassador since July 2010.