(Recasts with statements after meeting)
By Diego Ore and Andrew Cawthorne
CARACAS, April 8 (Reuters) - President Nicolas Maduro's government and Venezuela's main opposition group agreed on Tuesday to begin formal talks intended to halt the nation's worst political unrest in a decade.
Representatives of the Vatican and South American regional bloc Unasur have been invited to mediate.
Clashes between security forces and pro-government militants on one side, and hooded opposition demonstrators blocking streets on the other, have killed 39 people since mid-February, according to official figures.
Maduro, the 51-year-old successor to Hugo Chavez, led the government team at Tuesday's preliminary talks that were the first sit-down with the Democratic Unity (MUD) opposition coalition since the troubles began.
"We are sending a good signal to our country by sitting down to talk, converse and resolve our differences," Vice President Jorge Arreaza said after the meeting in a 17th century colonial building that houses the foreign ministry.
"We're not trying to convince the opposition to become 'Chavistas' nor are they trying to convince us to abandon the path of the revolution and socialism," he added.
Formal talks would begin in the next few hours, with Venezuela's crime and economic problems high on the agenda, he said. Those issues have been high on the litany of complaints from demonstrators in the streets since early February.
Tuesday's talks, set up by visiting Unasur foreign ministers, may take some heat out of a crisis that has also caused hundreds of injuries and arrests, and proved a further drag on Venezuela's ailing economy.
But they may disappoint hardliners in the opposition, who had been hoping to inspire a "Venezuelan Spring" and view Maduro's exit as the only solution.
MUD leader Ramon Guillermo Aveledo said the opposition would ensure that students, who have led the wave of protests, would not be forgotten in the talks. Dozens of student demonstrators remain detained, and there have been allegations of torture.
"We have agreed to the presence of a third party who will help us in this difficult path," Aveledo said, referring to the probable involvement of a Roman Catholic Church official.
One hardline opposition leader, Maria Corina Machado, dismissed the talks in advance.
"There cannot be dialogue when students, mayors and (another opposition leader) Leopoldo Lopez are prisoner, and repression continues," she said via Twitter.
Though there have been no new fatalities for several days, clashes have continued on the streets of Caracas and some other hotspots such as the western city of San Cristobal.
While the students have failed to bring millions or protesters out as they had hoped, they have shown persistence in building barricades on streets and using other nuisance tactics. Maduro accuses them of trying to promote a coup against him. (Editing by Lisa Shumaker)