* Chavez supporters show grainy video of Capriles aide
* Capriles sacks campaign official ahead of Oct. 7 vote
By Brian Ellsworth
CARACAS, Sept 13 (Reuters) - Venezuela's opposition presidential candidate Henrique Capriles kicked a top aide off his campaign on Thursday after vague corruption accusations by government leaders, potentially harming his bid to unseat socialist President Hugo Chavez.
Pro-Chavez legislators showed a grainy video of the aide receiving an envelope that they said contained cash that could be used to finance the opposition's campaign or to pay bribes.
The incident threatens to link Capriles with the OPEC nation's decades-long tradition of bribery and embezzlement of oil revenue just three weeks before the Oct. 7 election.
It comes a day after several people were hurt when supporters of both sides fought and threw rocks ahead of a campaign stop by Capriles, heating up a campaign already marred by sporadic clashes and virulent insults.
"He is out the campaign ... I will not allow anyone to use my name for personal benefit," Capriles said of Juan Carlos Caldera, an opposition legislator who had been the Capriles team's liaison to the electoral authority.
"This is what has destroyed (this country's) politics."
Caldera did not immediately respond to phone calls seeking comment. But an opposition official said Caldera would step aside while it "investigates and clears up" the issue.
The edited video first showed Caldera speaking to a person whose voice was distorted and face obscured on the screen.
Caldera was seen receiving an envelope from the person, who asked him to set up a meeting with Capriles. The legislator was later seen placing cash into a larger envelope.
Vice President Elias Jaua quickly weighed in via his Twitter account: "The #corruptloser Capriles told Juan Carlos Caldera to go get his cash."
Chavez leads the majority of the best-known polls, but they are notoriously controversial and divergent in Venezuela. One major firm has Capriles ahead.
The youthful former state governor has hoped to tap into public anger over alleged corruption by state officials. Chavez's critics and some of his disaffected supporters complain of seeing low-paid government officials driving fancy SUVs or taking lavish vacations.
In one famous 2007 incident, a business leader flying with Chavez to Argentina was stopped at an airport carrying a briefcase with nearly $1 million in cash.
The new allegations mostly overshadowed accusations by a judge formerly allied with Chavez who wrote a letter made public on Thursday that gave a detailed account of how he was ordered to rig the trials of the president's adversaries.
Former Supreme Court Justice Eladio Aponte, who fled the country in April, wrote in a sworn statement that he acted on Chavez's orders to give 30-year sentences to police officers charged with involvement in a bungled 2002 coup.
"I don't pretend to exonerate my responsibility for what I did ... I simply wanted to rest my conscience," said Aponte, who says Chavez's office routinely interfered in cases.
According to U.S. intelligence sources, he is cooperating with U.S. authorities by providing details about the Venezuelan government's links to drug trafficking.
Aponte's comments will likely cement the belief within the opposition that Chavez uses the court system to his own benefit but is unlikely to become a major campaign issue.
Among the myriad polling companies in Venezuela, respected Datanalisis put Chavez ahead by 12 points in July, though Capriles' numbers have been creeping up and another well-known pollster, Consultores 21, has him neck-and-neck. Both sides disregard unfavorable polls and say their candidate is ahead.
A third term for Chavez would add another six years to Venezuela's experiment with socialism, characterized by price and currency controls, confrontation with business and frequent nationalizations.
Critics say the president has the upper hand in the election thanks to liberal spending of public funds to boost his image, and the use of state media to promote his campaign.
Capriles is promising a Brazil-style balance of free markets and social protection.
Investors believe he would bring a more market-friendly economy following 14 years of Chavez. But they also believe he could face potential unrest or protests by oil industry workers loyal to Chavez who could refuse to recognize his leadership.