By Agencies

Henrique Capriles rejects ruling that would prevent him from challenging President Nicolas Maduro in 2018 polls.

Venezuelan authorities have banned top opposition leader Henrique Capriles from public office for 15 years, the latest move in an increasingly tense power struggle in the crisis-hit country.

State comptroller Manuel Galindo imposed a "sanction of disqualification from exercising public office for a period of 15 years," his institution said in a ruling made public by Capriles himself on Friday.

The punishment deals a blow to the opposition after stepped-up protests this week and accusations that President Nicolas Maduro is leading the country to dictatorship and cracking down on dissent.

Capriles said on Twitter that he rejected the move and insisted he would retain his post as governor.

The ruling said the sanction was due to "administrative irregularities" by Capriles in his post as governor of the northern state of Miranda.

The move effectively bans Capriles, a two-time presidential candidate, from running against socialist Maduro in a general election due next year.

If effective, it will remove from the political ring one of the most prominent contenders in the centre-right opposition that is pushing to remove Maduro from office.

Capriles branded the move part of what the opposition alleges is a "coup" by Maduro, who is resisting opposition calls for a vote on removing him from power.

"This is all part and package of the internal coup," Capriles said on Twitter.

"The only one who is disqualified in this country is you, Nicolas Maduro, you and the corrupt drug-trafficking leadership that is with you!"

The comptroller's office notification to Capriles said he had 15 working days to appeal the decision at that office or 180 days to ask for its annulment at the Supreme Court. Both are pro-government and unlikely to overturn the decision.

Capriles lost narrowly in the 2013 election that brought Maduro to the presidency after the death of Maduro's mentor Hugo Chavez.

Political crisis

Venezuela's political crisis intensified last week when the Supreme Court issued rulings curbing the powers of the opposition-controlled legislature.

The rulings by the court, which has consistently ruled in Maduro's favour during the crisis, drew international criticism of Maduro's camp.

The court revoked the moves days later, but the opposition maintained its claim that Maduro's side was attempting an institutional "coup d'etat."

The collapse in prices for Venezuela's crucial oil exports has sapped the country's revenues, prompting shortages of food, medicine and basic goods along with a surge in violent crime.

The opposition blames Maduro for the economic crisis. He says it is due to a capitalist conspiracy.

Violence erupted for a third straight day on Thursday at protests against Maduro, leaving one demonstrator dead.

The wave of protests has revived fears of broader unrest in Venezuela, where 43 people were killed during riots in 2014.

The country has undergone three attempted military coups since 1992.