Venezuelan President Hugo Chavez came out of cancer surgery overnight in Cuba and is recovering in a hospital, two sources said on Tuesday, but there was still no official word on the socialist leader's condition.

The 57-year-old returned to Havana last week for more surgery despite repeatedly saying he was cured after two procedures last year. That has fueled doubts about his ability to campaign for re-election in October, or to govern if he won.

A prominent opposition-leaning Venezuelan journalist, Nelson Bocaranda, said the president was well after the exploratory procedure at Havana's Cimeq Hospital.

A medical source close to the team that had been treating him in Caracas said the surgery lasted 90 minutes.

Chavez's government responded to criticism of the secrecy surrounding his condition by naming Health Minister Eugenia Sader last week as its spokesperson on the issue.

But four days after Chavez bid an emotional farewell to throngs of cheering supporters in the Venezuelan capital, there has been no official comment. One senior administration source told a Reuters reporter to be patient.

Before he left on Friday, Chavez said he would need surgery on a probably-malignant lesion found in his pelvis where a large cancerous tumour was removed last June. He has also said he might need radiation treatment following the latest operation, raising the prospect of another lengthy convalescence.

Chavez's health situation could hobble his re-election campaign, when he normally would want to crisscross the South American country during the run-up to an October 7 vote that will pit him against opposition candidate Henrique Capriles, a 39-year-old state governor.

Before the announcement that he would need more surgery, opinion polls showed Venezuelans broadly split with a third pro-Chavez, a third pro-opposition and a third undecided.

But the polls indicate Chavez might have a slight edge in voter enthusiasm - attributed to his popularity among the poor and an increase in welfare spending for the most needy.

While the president may get a sympathy bump in the polls in the weeks ahead, voter perceptions of weakness in Chavez - particularly in contrast with Capriles' youthful image - could offset that.

Chavez's latest health problems have pushed the OPEC nation's widely traded bonds higher on investor hopes for a more market-friendly government in the future.

Chavez has avoided grooming a successor and has dominated the political stage himself since his first election win in 1998, so rumours abound as to who from his inner circle could take over if he were to be incapacitated.

None of his closest supporters share his man-of-the-people charisma, or the political and rhetorical talents that have forged his close connection with Venezuela's poor majority.

(Editing by Will Dunham)