* Opposition calls Maduro illegitimate leader
* Government says Capriles orchestrated post-vote violence
* Opposition deputies bruised in punch-up in parliament
Opposition and government supporters flooded Venezuelan streets in rival May Day marches on Wednesday as a continuing dispute over the results of last month's presidential vote kept political tensions high in the OPEC nation.
On Tuesday, opposition deputies were beaten in a fracas in Congress resulting from their refusal to recognize the presidency of Nicolas Maduro, who narrowly won the April 14 election triggered by the death of socialist leader Hugo Chavez.
Government officials, meanwhile, have threatened to jail opposition leader Henrique Capriles for allegedly orchestrating violent demonstrations that killed nine people after the vote. Most foreign governments, with the exception of the United States, have recognized the election results.
The volatile situation underscores the challenges of the "Chavismo" movement to maintain Hugo Chavez's self-styled revolution without his messianic but micro-managing leadership.
"We're not afraid of the government, even if they threaten, beat, and insult us - we're going to continue demonstrating like we are today," said Graciela Perez, 61, a housewife, marching through the affluent east side of the capital of Caracas.
"We only want the truth to be known - that they stole the elections."
A renewal of the post-vote violence appeared unlikely because the rival marches in Caracas, involving tens of thousands of people on each side, will not cross paths. Similar marches took place elsewhere in the country.
Maduro, a 50-year-old former bus driver, will likely use the labor day celebration to tout the working-class roots that helped make him Chavez's chosen successor.
"We're here in the streets because this is a workers' government that represents the people," said Luis Graterol, an airport worker at a pro-government march in central Caracas.
Vendors sold pictures of the late Chavez to marchers wearing signature-red shirts, some of which were adorned with Maduro's face. One sign read "Capriles: fascist assassin."
The opposition dismisses Maduro as an illegitimate leader who usurped power through voting-day irregularities. They have called a post-vote audit by the elections council a farce and are challenging the results in the nation's top court.
Leaders of the national legislature, which is controlled by the ruling Socialist Party, have refused to give opposition deputies the floor unless they recognize Maduro.
During Tuesday's session, legislators allied with Capriles raised a banner that read "Coup in the Parliament" to protest the measure they describe as censorship.
Video footage shows Socialist Party legislators scrambling to pull the banner down and one man repeatedly punching an opposition deputy in the face, leaving him bloodied and bruised.
Another deputy said she was thrown to the floor and kicked while Congress chief Diosdado Cabello, a close Chavez ally, stood watching with a smile on his face.
Cabello told state television on Wednesday that he regretted the incident, but blamed the opposition for what happened.
"Tempers are hot, but that's because these gentlemen of the opposition have not recognized state institutions and generated violence on April 14 and 15," he said.
The legislature has opened a special commission to investigate the violence that resulted from opposition demonstrations to demand a full recount.
The prisons minister has said she is preparing a cell for Capriles.
In recent days, the government has arrested a retired general turned opposition leader and an American film-maker on charges of stirring up the protests to destabilize the country.
Chavez died on March 5 after a two-year battle with cancer, prompting an outpouring of grief by supporters.
His 14-year rule made Chavez a hero to millions of poor Venezuelans who were thankful for his oil-funded social largesse, helping him win repeated elections.
Adversaries called him an autocrat and a demagogue who squandered unprecedented oil income, persecuted rivals and weakened the economy by expropriating hundreds of businesses.