By Fabian Cambero and Andrew Cawthorne
CARACAS (Reuters) - Venezuela's opposition on Monday ruled out returning to Vatican-led talks with President Nicolas Maduro's government unless it makes major concessions amid a crushing economic crisis and bitter political standoff.
The opposition Democratic Unity coalition blames Maduro for the OPEC nation's shrinking and dysfunctional economy and wants to bring forward the next presidential vote, due in late 2018.
However Maduro, 54, the self-declared "son" of late socialist leader Hugo Chavez, accuses the opposition of seeking a coup and sabotaging the economy to undermine him.
A Papal envoy, South American bloc Unasur and former heads of government from Spain, Panama and the Dominican Republic brought the feuding sides together at the end of October.
But the opposition walked out earlier this month, saying officials were reneging on accords to allow humanitarian aid, reform the national election board, free jailed activists and restore the National Assembly's powers.
"If these demands ... have not been satisfied by Jan. 13, obviously there will be no conditions to re-establish dialogue," said coalition head Jesus Torrealba, referring to the next potential date for talks mooted by mediators.
"They are mocking the Venezuelan people and the international community," he told reporters.
Maduro, whose popularity has hit its lowest level of under 20 percent, according to pollster Datanalisis, said his team would be ready for Jan. 13 talks come what may.
"I want to affirm to Pope Francis ... my commitment to dialogue, peace and the word of God," he told a radio show. "If not talking means Torrealba is going to take up arms and call for an intervention in Venezuela, he will never achieve it."
Opposition leaders say the coalition needs a re-launch in the New Year after the dialogue stalled momentum from large street protests and a symbolic trial of Maduro in the Assembly.
The president has threatened that the opposition-led legislature may not exist much longer. The government-leaning Supreme Court has ruled it is in "contempt" of the law.
Hardline opposition leaders are pushing for a civil disobedience campaign, but moderates believe that could lead to more violence and play into the government's hands by allowing Maduro to depict them as irresponsible troublemakers.
Opposition protests in 2014 led to 43 deaths and marches this year have resulted in clashes with security forces.
Venezuela's 30 million people have had an austere Christmas, with many unable to afford traditional meals, presents and holidays at the beach.
Inflation in Venezuela is the world's highest and many products are scarce.
(Reporting by Fabian Cambero and Andrew Cawthorne; Editing by Dan Grebler and Paul Tait)