The United States on Monday imposed sanctions on three Venezuelans and 20 companies for narcotics trafficking activity, as it seeks to increase pressure on socialist President Nicolas Maduro.

Of the newly sanctioned companies, 16 are based in Venezuela and four in Panama. They are owned or controlled by the three individuals, the U.S. Treasury said in a statement on its website.

"We will deny corrupt Venezuelan regime officials access to the U.S. financial system as we work with international partners to support the Venezuelan people in restoration of democracy and a return to prosperity," said U.S. Treasury Secretary Steven Mnuchin.

U.S. Vice President Mike Pence also called for the Organization of American States to suspend Venezuela's membership in the 35-nation group.

Pence, in a speech to the OAS, urged Maduro to suspend elections scheduled for May 20, saying they would be a "fraud" and a "sham." He also urged Venezuela's neighbors in the hemisphere to step up their own measures against Caracas.

"The time has come, first and foremost, to cut off Venezuela's corrupt leaders from laundering money through your financial systems. Secondly, the time has come to enact visa restrictions that prevent Venezuela's leaders from entering your nations. And finally, we call on all freedom-loving nations across our hemisphere to hold Maduro accountable for destroying Venezuelans' democracy," Pence said.

Venezuela's Information Ministry did not respond to a request for comment. Maduro, himself subject to sanctions last year, regularly laughs off Washington's disapproval and blames the U.S. "empire" for his country's economic woes, saying it is trying to undermine his administration.

Pence previously has urged the international community to increase pressure on Maduro, who the United States blames for a deep recession and hyperinflation in Venezuela that have caused shortages of food and medicine and a flood of migrants into neighboring countries.

U.S. President Donald Trump's administration has already imposed some financial and individual sanctions on Maduro's government, accusing senior officials of rights abuses and corruption.

The Trump administration has also been weighing new oil-related sanctions on a Venezuelan oil services company and on insurance coverage for tankers carrying Venezuelan oil.

Oil prices rose to their highest levels since late 2014 on Monday, boosted by fresh troubles for Venezuelan state oil company PDVSA and a looming decision on whether the United States will reimpose sanctions on Iran over its nuclear program.