Venezuelan President Nicolas Maduro ordered a reduction in the number of officials allowed to work at the U.S. embassy in Caracas and said several Americans were detained as tensions mounted between the two countries.

U.S. officials who remain will be required to obtain approval for any meetings they hold in the country, Maduro said Saturday on state television. He presented a folder during the speech that he said contained evidence embassy officials were working to destabilize the South American country.

“I have the proof here,” Maduro said after a pro- government march in Caracas. “Videos, audio recordings and testimonies of the illegal, conspiratory activities of various functionaries of the U.S. government. I’ve thought about it very well. It’s for our homeland, our sovereignty.”

A U.S. embassy official in Caracas declined Saturday to comment after Maduro’s speech. The U.S. State Department said Feb. 19 that accusations it was involved in coup plotting were “baseless and false” and an attempt to distract attention from the country’s economic woes. A White House spokesman, Patrick Ventrell, referred questions to the State Department, which didn’t immediately respond to a request for comment.

Buffeted by plunging oil prices, Venezuela’s economy will contract 7 percent this year, according to the International Monetary Fund, while inflation, which accelerated to 69 percent in December, is the fastest in the world.

Bush Banned

U.S. citizens who travel to Venezuela will now be required to obtain visas, Maduro said, and some current and former U.S. officials will be banned from entering the country. They include former President George W. Bush, former Vice President Dick Cheney, former central intelligence director George Tenet and Senator Marco Rubio, a Florida Republican who is running for president.

Another U.S. politician banned by Maduro, Republican Representative Mario Diaz-Balart of Florida, responded in a Twitter message: “I’ve always wanted to travel to a corrupt country that is not a free democracy. And now Castro’s lap dog won’t let me!”

Venezuelan authorities detained a U.S. pilot of Latino origin in the western Tachira state with “all kinds of documentation,” Maduro said without providing additional details.

“In the past several days, we’ve detected activity and captured several Americans involved in espionage,” Maduro said. “To protect our country, we’re going to introduce an obligatory visa system for any American who wants to come here. They’ll have to pay in dollars what Venezuelans have to pay to go to the U.S.”

Missionaries Freed

Four American missionaries detained by authorities in Venezuela earlier this week have been freed and are on their way back to the U.S., North Dakota Senator John Hoeven, a Republican, said Saturday.

In February, the U.S. expanded visa restrictions on Venezuelan government officials believed to be complicit in human-rights abuses and public corruption. Maduro said Saturday that Venezuela wouldn’t accept any U.S. sanctions.

“The U.S. thinks it owns the world,” Maduro said. “They give their opinions all over. Something happens in Asia, and a spokesperson comes to speak out against it. What is that? Are we going to accept a world government?”

Maduro said he asked the Union of South American Nations to send its foreign ministers to Caracas so that he could present proof of U.S. intervention in Venezuela.

Sporadic protests across Venezuela have broken out over the past month as Maduro cracked down on opposition politicians with the arrest of Caracas opposition Mayor Antonio Ledezma.

Venezuela’s public prosecutor charged a national police officer in the death of a teenage boy during a protest in the western city of San Cristobal on Feb. 24, the first death this year after anti-government protests in 2014 claimed 43 lives.

Pope Francis, the leader of the world’s 1.2 billion Catholics, prayed Sunday for the victims of violence in Venezuela and said the country was “again living moments of acute tension,” Vatican Radio reported.