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WASHINGTON, July 17 (Reuters) - U.S. President Donald Trump threatened on Monday to take "strong and swift economic actions" if Venezuelan President Nicolas Maduro goes ahead with plans to create a super-legislature known as a Constituent Assembly in a July 30 vote.

"Yesterday, the Venezuelan people again made clear that they stand for democracy, freedom and rule of law. Yet their strong and courageous actions continue to be ignored by a bad leader who dreams of becoming a dictator," Trump said in a statement issued by the White House.

"The United States will not stand by as Venezuela crumbles. If the Maduro regime imposes its Constituent Assembly on July 30, the United States will take strong and swift economic actions," Trump said.

Maduro's foes are demanding a presidential election and want to stop the leftist leader's plan to create the Constituent Assembly, which would have the power to rewrite the constitution and annul the opposition-led legislature.

On Sunday, 98 percent of opposition supporters in an unofficial vote rejected the proposed assembly.

Maduro insists opposition leaders are U.S. pawns intent on sabotaging the economy and bringing him down through violence as part of an international right-wing conspiracy led by Washington and fanned by private domestic and foreign media.

Senior White House officials told Reuters last month the Trump administration was considering sanctions on Venezuela's vital energy sector, including state oil company PDVSA, a major escalation in U.S. efforts to pressure the country's government amid a crackdown on the opposition.

The idea of striking at the core of Venezuela’s economy, which relies on oil for some 95 percent of export revenues, has been discussed at high levels of the administration as part of a wide-ranging review of U.S. options.

The White House officials, speaking on condition of anonymity, told Reuters the United States could hit PDVSA as part of a “sectoral” sanctions package that would take aim at the OPEC nation’s entire energy industry for the first time.

They made clear the administration was moving cautiously, mindful that if such an unprecedented step was taken, it could deepen the country’s economic and social crisis, in which millions suffer food shortages and soaring inflation.

Another complicating factor would be the potential impact on oil shipments to the United States, for which Venezuela is the third largest oil supplier after Canada and Saudi Arabia. It accounted for 8 percent of U.S. oil imports in March, according to U.S. government figures.

(Reporting by David Alexander; Additional reporting by Girish Gupta in Caracas and Matt Spetalnick in Washington; Editing by Peter Cooney)