Venezuela's opposition has spurned the crisis talks that the government called to try to halt three weeks of protests that have left 14 dead.
President Nicolas Maduro had called a "national peace conference," but only the business federation and the Roman Catholic church confirmed they would attend.
The main political opposition coalition on Wednesday denounced the planned talks as political theatre and an insult to the slain protesters.
"We will not lend ourselves to a sham dialogue that would end in a mockery of our countrymen," the opposition MUD said, in a letter to Vice President Jorge Arreaza.
The opposition's main leader Henrique Capriles had earlier said he would not attend, dismissing the talks as a government photo op.
Oil-rich but deeply divided Venezuela has been swept by student-led protests since February 4, posing the greatest challenge yet to Maduro's 11-month-old government.
Those who are on the streets say public anger over shortages of food and other basics, soaring inflation and rampant crime have served as kindling for these protests.
"Unless we all get out there and protest, we are not going to be able to get out of this really complicated situation," said university student Andres Contreras, out on a Caracas street.
Venezuelan authorities said Wednesday they had arrested five intelligence agents for suspected ties to killings during protests against Maduro's government.
On Monday, nine people were arrested in the same case including three SEBIN intelligence service members, and the rest police.
"Why should we have to live like this?" demanded demonstrator Adriana Diaz, a 48-year-old lawyer banging on a cooking pot, on of the symbols of opposition defiance.
"The government should listen to people, and change the economic system."
Maduro has responded to the street protests with force, arresting scores of demonstrators as well as a prominent opposition leader, Leopoldo Lopez.
