Rival supporters in Venezuela's presidential election fought and threw stones on Wednesday before a campaign stop by opposition leader Henrique Capriles less than a month before an October 7 vote.

In the worst flareup since the campaign formally began on July 1, some people were hurt and both sides blamed the other for the violence at the country's main port, Puerto Cabello.

TV footage showed dozens of people running, while some hurled rocks. At least one car was set on fire.

Capriles wants to unseat President Hugo Chavez and end 14 years of the socialist leader's self-styled revolution. There have been a handful of clashes on the campaign trail so far.

"These acts are not spontaneous, there is someone responsible," the 40-year-old state governor told a rally after the clashes, blaming Chavez directly.

"It is him, and I say this directly: it is you who wants this scenario, you who wants to spread fear, you who wants Venezuelans to continue fighting each other."

Venezuela's election has so far generated much less violence than some locals had feared. But with a huge number of guns in public hands, and tempers becoming frayed as voting day nears, there remains the risk of a more serious confrontation.

Chavez's supporters blamed the opposition for Wednesday's clash, which closed the main road to Puerto Cabello's airport and forced Capriles to arrive in the area by small boat instead.

State media said 25 people had been hurt, while an opposition TV network gave a lower number of wounded.

"We were surprised by a shower of rocks, fireworks and petrol bombs ... which caused a large number of casualties," Rafael Lacava, the local mayor and a Chavez ally, told state TV.

"We were attacked by an advance group, which (Capriles) always sends on ahead when he holds these type of events."

Chavez leads the majority of the best-known polls, but they are notoriously controversial and divergent in the South American country and one major company puts Capriles ahead.

Among the myriad polling companies in Venezuela, respected Datanalisis had 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 discount unfavorable polls, and say their candidate is ahead.