* Chavez recovering from cancer surgery in Cuba
* Socialist leader was re-elected in October
By Deisy Buitrago
CARACAS, Dec 15 (Reuters) - Venezuelan President Hugo Chavez has recovered "full intellectual capacity" after a six-hour cancer operation in Cuba this week, an official said on Saturday, but offered few details on the socialist firebrand's physical condition.
Chavez's health weakened sharply after his October re-election, casting doubt on the future of his "21st century socialism," which has won broad popular support but also infuriated adversaries who call him an aspiring dictator.
Science and Technology Minister Jorge Arreaza, who is also Chavez's son-in-law, said in a phone call from Havana broadcast over state television that Chavez was continuing to recover.
"He is in a process of progressive stabilization and has full intellectual capacity, sufficient to send this message to the Venezuelan people," said Arreaza, who is accompanying Chavez during his recovery.
"We recognize that there were some moments of tension, mostly on (Tuesday and Wednesday), but we have overcome them one by one," he said.
The call came during a celebration of the eighth anniversary of the founding of the leftist ALBA bloc of nations championed by Chavez as an anti-U.S. alliance of socialist nations.
Bolivian President Evo Morales and Ecuador's Foreign Minister Ricardo Patino joined a celebration in downtown Caracas largely dedicated to celebrating Chavez's leftist policies and wishing him a swift recovery.
The government has provided no details on the situation of his cancer, which has returned twice since it was originally diagnosed in June 2011 and has required four operations. Chavez has said the cancer struck his pelvic region, but has not given any further details.
The information minister this week conceded Chavez may not be in condition to begin his third term on Jan. 10, as mandated by the constitution.
If he cannot, fresh presidential elections would be called within 30 days, with Vice President Nicolas Maduro running as the ruling Socialist Party's candidate.
The opposition would likely field the youthful Henrique Capriles, who lost to Chavez in October but gave the opposition its strongest showing in a presidential race against him.
That will depend on Capriles winning reelection for governor in the state of Miranda against Chavez protege and former Vice President Elias Jaua in Sunday's regional elections.
If Caprles loses that vote, other opposition hopefuls might push him aside. Chavez's adversaries hope to retain seven of the 23 governorships they currently hold, and may view the ballot as a dry run for a possible presidential election down the road.
Energy companies are keenly watching events and hope a change in government will lead to greater access to the country's vast crude oil reserves - the world's largest. Years of combative state takeovers have alienated major oil companies.
Investors drawn to Venezuela's highly traded bonds are hoping for more fiscal responsibility after a year of blowout campaign spending.