“The government is desperately sowing lies,” said Capriles, who called supporters onto the streets after the disputed election results, but has since urged only peaceful protests.

“I have a clear conscience ... the people who stole the election want the country to stay divided.”

The National Assembly said on Twitter that a special committee would begin meeting on Monday to investigate the violence. “The commission will determine responsibility for violent actions directed by Capriles,” it said.

Government legislator Pedro Carreno, who will head the committee that does not include any opposition parliamentarians, called Capriles a “murderer” during Wednesday’s announcement.

“Sooner rather than later, he will have to pay for those crimes,” Carreno said, describing the death of an 11-year-old girl as the result of “fascism.”

Inside Venezuela, reports of the violence have varied, with state media painting an image of pro-opposition mobs burning government offices and health facilities.

Opposition media have quoted relatives of victims saying some of the deaths had nothing to do with the political tensions, and shown images of facilities functioning normally.

In a sustained assault against Capriles from numerous senior officials, National Assembly head Diosdado Cabello called him a “fascist murderer,” while Prisons Minister Iris Varela said a jail cell and rehabilitation therapies awaited him.

Capriles, a 40-year-old state governor who promises Brazilian-style pro-business policies mixed with strong social protections, confounded opinion polls to run a close finish against Maduro in the vote to succeed late socialist leader Hugo Chavez.

Despite an initial large gap in the polls, emotion around the death of Chavez who had endorsed him as successor, as well as a powerful state apparatus behind his election campaign, Maduro won by less than 2 percentage points.

Capriles said the ballot was marred by thousands of irregularities, including intimidation of voters at poll centres, and demanded a recount.

The election board is carrying out a partial audit but has said that will not change the result.

Capriles told reporters the opposition would only wait until Thursday for concrete details on the process. “We will not accept a joke audit,” he said. “It’s time to get serious.”

He did not say what would happen if the deadline were not met. Earlier during his news conference, Capriles had sharply criticized a “cadena” broadcast - which all local channels are required to show live - that the government played on Tuesday.

Comparing it with videos of his speeches, the opposition leader said his words had been taken out of context to make it look like he was whipping up violence. Moments later, his press conference was interrupted - by a repeat of the same “cadena.”

That triggered a noisy demonstration in at least one wealthier Caracas neighbourhood, with Capriles supporters banging pots and pans from windows in a traditional form of protest.

“They want to stop people seeing the truth,” he said later.

Both Maduro and Capriles have called on their supporters to march again on May 1 in another potential flashpoint for the OPEC nation of 29 million people.

In 2004, Capriles was jailed for four months after being accused of stirring up violence during a protest at the Cuban embassy two years earlier. He denied the accusation, saying he was mediating there. The case was set aside.