BRUSSELS (Reuters) - The European Union said on Thursday it could impose further sanctions on Venezuela if it believes democracy is being undermined there, after the South American country’s president called for elections next month that the main opposition has said it will boycott.

FILE PHOTO: Venezuela's President Nicolas Maduro speaks during a gathering with supporters at Miraflores Palace in Caracas, Venezuela April 4, 2018. REUTERS/Marco Bello/File photo

EU foreign affairs chief Federica Mogherini said in a statement she regretted the way the authorities under President Nicolas Maduro had called the May 20 presidential elections without a consensus on the “conditions for a credible and inclusive electoral process.”

In response, Venezuela’s foreign ministry said in a statement: “The European Union and its member states show their regrettable subordination to the opinions of the U.S. government.”

Venezuela has tumbled into an economic and social crisis, with millions suffering food and medicine shortages, hyperinflation and growing insecurity, which critics say is the result of the dysfunctional policies of Maduro’s government. The collapse has driven an estimated 3 million people to flee the country.

Maduro, who blames the downturn on an “economic war” led by the opposition and the United States, is seeking re-election in the May 20 vote.

The main opposition coalition is boycotting the vote, and the country’s two most popular opposition leaders have been banned from competing.

“The European Union will monitor closely the electoral process and related developments on the ground and stands ready to react through appropriate measures to any decision or action that might continue to undermine democracy, the rule of law and human rights situation in the country,” Mogherini added.

She said all parties should be allowed to contest fair elections in the country.

Last week, U.S. Vice President Mike Pence told regional leaders that more must be done to isolate Maduro, and that Washington would not stand “idly by” as the country crumbles.

The EU has already imposed sanctions on Venezuela such as an arms embargo, asset freezes and a travel ban for certain officials, accusing Maduro’s government of breaches of human rights and undermining democracy.