Venezuela's Supreme Court threw into doubt the presidential campaign of a prominent opposition leader on Monday by upholding a bar on him holding office.

The Supreme Court dismissed as "unfeasible" a decision issued last month by the Costa Rica-based Inter-American Court of Human Rights that demanded Venezuelan electoral officials allow Leopoldo Lopez to run for office.

The former Caracas district mayor was on a list of politicians blacklisted due to corruption investigations, but he insists he is innocent and notes he was never sentenced in a court.

In upholding his disqualification from holding office, the Supreme Court appeared to deal a significant blow against a promising opponent of President Hugo Chavez. Yet in a ruling that left much uncertain, the court also said Lopez is still able to be a candidate if he chooses.

Supreme Court president Luisa Estella Morales told reporters that Lopez "can freely sign up and participate in elections," including next year's presidential vote. But Morales declined to answer whether Lopez would be allowed to hold office if he were elected president.

"It's a future and uncertain situation that isn't within the judicial branch's analysis at this time," Morales said, adding that in such a scenario, "undoubtedly we would have to give a response and an interpretation, but at this time it would be to pass judgment on uncertain events."

Lopez was barred from holding office by Venezuela's top anti-corruption official starting in 2008.

The temporary prohibition resulted from multiple allegations. One is that a nonprofit group to which Lopez belonged had received donations from 1998 to 2001 from the state oil company Petroleos de Venezuela SA, where he and his mother worked at the time.

The comptroller general also sanctioned Lopez in 2004 for alleged irregularities in the movement of funds from one portion of his local budget to another. The measures barring him from office, which took effect in 2008, are supposed to be in effect until 2014.

Lopez challenged his disqualification in the regional human rights court arguing that his political rights were violated, and that court ruled in his favor on Sept. 1.

But Venezuela's Supreme Court said in Monday's ruling that the measure barring Lopez from holding public office "does not impede him from exercising his political rights." It said the "administrative disqualification ... is directed only at temporarily impeding the exercise of public duties."

Lopez has announced plans to run in a February primary vote that will pick a unity candidate to challenge Chavez in the October 2012 election. When Lopez launched his campaign last month, he challenged Chavez to accept him in the race, implying that the president wielded influence over the judiciary.

"Since 2008, he's been looking for a mechanism to remove me from the political game," Lopez said last month. "Mr. President, I ask myself: ... Are you afraid of me?"

Chavez strongly criticized the Costa Rica-based court after its ruling, saying it's part of an international system that "protects the corrupt and obeys the mandate of the (U.S.) imperial power."

Lopez's departure from the presidential race would shake up the field of candidates, in which polls show he is a strong contender though trailing others such as state governors Henrique Capriles and Pablo Perez.

Lopez's campaign said in a statement that he would publicly respond to the Supreme Court decision Tuesday. The campaign also said the decision "damages international agreements signed and ratified" by Venezuela. Human rights activists had joined Lopez in urging Venezuela to respect the ruling by the rights court.

Morales said the court decided it was "unfeasible" to nullify anti-corruption measures that had been properly imposed by the comptroller general.

"What we think isn't feasible is for Venezuela to go backward in the advances it has made in the fight against corruption," Morales said, noting that Venezuela has also signed international conventions committing it to fighting corruption.

A coalition of Venezuela's main opposition parties, known as the Democratic Unity Table, condemned the Supreme Court ruling, saying in a statement that it violated the constitution as well as international treaties.

"The Venezuelan state is obligated to accept the rulings of the Inter-American Human Rights Court," the opposition coalition said. "We see this deplorable decision as another reason to bring about a peaceful, democratic and constitutional change."

The coalition said it would denounce the decision before Jose Miguel Insulza, secretary-general of the Organization of American States.

Pro-Chavez lawmaker Cilia Flores denied that the Supreme Court's decision represents any violation of democratic liberties.

"There's complete democracy here, total freedoms, outright participation," Flores said after the ruling was announced.

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Associated Press writer Christopher Toothaker contributed to this report.