VATICAN-mediated talks between Venezuela’s socialist government and US-backed opposition got under way on Sunday night.

But 15 affiliate parties of the Democratic Unity Roundtable (Mud) coalition shunned the negotiating table.

Instead they penned a joint letter to Mud secretary-general Jesus Torrealba, demanding that he only negotiate United Socialist Party (PSUV) President Nicolas Maduro’s overthrow and the release of several political activists.

“It has to be very clear from the outset that the aim is agreeing on the terms of a democratic transition in the remainder of 2016,” they wrote.

The dissident parties repeated their demand for a presidential recall referendum before the end of the year and the release of prisoners including far-right Popular Will party leader Leopoldo Lopez.

Mr Lopez was jailed last year for almost 14 years for inciting a 2014 street protest movement that left 43 dead.

Vatican envoy Archbishop Claudio Maria Celli opened the meeting at the Alejandro Otero art museum in the capital Caracas, calling for “concrete outcomes” to “show the goodwill of both sides.”

Former Spanish prime minister Jose Luis Rodriguez Zapatero and ex-presidents Leonel Fernandez of the Dominican Republic and Martin Torrijos of Panama, who mediated earlier indirect talks, were also present.

Mr Maduro said he was ready to “take on the challenge” and “find common ground in the interests of the great majorities.

“We’re giving a chance to disarm the hatred, the intolerance, and open the door to love among the Venezuelans,” he said.

Mud MP Stalin Gonzalez told Globovision TV: “The government must give a sign it wants to resolve the crisis with dialogue and not win a few more days in power.”

Foreign Minister Delcy Rodriguez, speaking from the Iberoamerican summit in Cartagena, Colombia, hoped the talks would head off an “unconstitutional and undemocratic overthrow” of the elected government.

A Mud march on the Miraflores presidential palace has been called for Thursday.

But last Friday’s 12-hour “general strike” called by the Mud was a failure, according to Mr Maduro, with most businesses and services staying open.

Public transport was only slightly quieter than usual and expensive private universities were some of only a few institutions to close.

However, an anti-government march last Wednesday was reported to have attracted thousands of supporters in Caracas and other Venezuelan cities.