CARACAS (Reuters) - Venezuela's President Nicolas Maduro warned on Tuesday that he and supporters would take up arms if his socialist government was violently overthrown by opponents who have been on the streets protesting for three months.

"I'm telling the world, and I hope the world listens after 90 days of protest, destruction and death," Maduro said in reference to anti-government unrest that has led to at least 75 deaths in the OPEC nation since April.

"If Venezuela was plunged into chaos and violence and the Bolivarian Revolution destroyed, we would go to combat. We would never give up, and what couldn't be done with votes, we would do with weapons, we would liberate the fatherland with weapons."

Maduro, 54, was speaking at a rally to promote a July 30 vote for a special super-body called a Constituent Assembly, which could rewrite the national charter and supersede other institutions such as the opposition-controlled congress.

He has touted the assembly as the only way to bring peace to Venezuela. But opponents, who want to bring forward the next presidential election scheduled for late 2018, say it is a sham poll designed purely to keep the socialists in power.

They are boycotting the vote, and protesting daily on the streets to try and have it stopped. Opposition leaders call Maduro a dictator who has wrecked a once-prosperous economy, while he calls them violent coup leaders.

Maduro, who accuses Washington of backing his opponents and seeking to control the nation's oil wealth, said the "destruction" of Venezuela would lead to a huge refugee wave dwarfing the migrant crisis in the Mediterranean.

"Listen, President Donald Trump," he said.

"You would have to build 20 walls in the sea, a wall from Mississippi to Florida, from Florida to New York, it would be crazy ... You have the responsibility: stop the madness of the violent Venezuelan right wing."

Opposition to the July 30 vote has come not just from Venezuelan opposition parties, but also from the chief state prosecutor Luisa Ortega and onetime government heavyweights like former intelligence service boss Miguel Rodriguez.

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At a news conference on Tuesday, Rodriguez criticized Maduro for not holding a referendum prior to the Constituent Assembly election, as his predecessor Chavez had done in 1999.

"This is a country without government, this is chaos," he said. "The people are left out ... They (the government) are seeking solutions outside the constitution ... That deepens the crisis."

(Reporting by Silene Ramirez, Deisy Buitrago and Andreina Aponte; Writing by Andrew Cawthorne; Editing by Andrew Hay)