Venezuela President Nicolas Maduro said Saturday that his government had captured U.S. citizens involved in "espionage activities," amid heightened tensions between the two nations, according to Reuters.
"We have captured some U.S. citizens in undercover activities, espionage, trying to win over people in towns along the Venezuelan coast," he said at a rally, according to the news agency.
He also said an American pilot of Latin descent captured in the city of Tachira, near the Colombian border.
"In Tachira we captured a pilot of a U.S. plane (who is) of Latin origin (carrying) all kinds of documentation," Maduro said, according to Reuters, though he didn't offer any details on whether the individual had ties to the U.S. military or was merely a private citizen with a pilot's license.
A spokesperson at the U.S. State Department told CBS News the department was aware of the reports, but could not offer any immediate confirmation.
Relations between the two countries have been steadily deteriorating. Earlier this month, Maduro accused the U.S. of working with local opposition groups to stage a coup that involved bombing the presidential palace. Washington called the accusation ludicrous.
Also on Saturday, Venezuela released four missionaries from North Dakota who were detained several days ago. They were banned from the country for two years.
Bruce Dick, lead pastor at Bethel Evangelical Free Church in Devils Lake, North Dakota, said the three men and one woman were released Saturday morning after being in custody since Wednesday.
Dick said the missionaries were taken from Ocumare de la Costa, a small coastal town where they have been working to establish a church, to the city of Maracay. He said they were steadily questioned by authorities over the approximately three days, but couldn't say what they were questioned about.
The missionaries were treated well, Dick said, adding that they were able to keep their cellphones and send text messages and make brief phone calls to loved ones.
"They didn't fear for their lives or anything, it was just question after question," he said.
Maduro said Saturday he will limit the number of U.S. diplomats allowed to work in Venezuela and also will require U.S. citizens to apply for visas if they want to visit.
The two countries have not exchanged ambassadors since 2010. Nonetheless, they have continued to exchange diplomatic staff. On Saturday, Maduro said the U.S. has far more officials in Venezuela than his socialist government has in the U.S.
"They have 100 diplomats and we have 17," Maduro said.
In an address that all Venezuelan television and radio stations were required to carry, Maduro addressed President Obama directly, saying he has "arrogantly" refused to engage in talks to resolve the issues between the two countries.
"I'm very sorry, Mr. President, that you have gone down this dead end," he said.
Maduro asked that the changes regulating diplomats be implemented immediately, within the limits of the Vienna Convention on Diplomatic Relations. Among other things, U.S. diplomats will be required to seek approval from the Foreign Ministry for meetings they conduct here.
Venezuela will also start charging tourists the same visa fees the U.S. charges Venezuelans. Maduro did not specify when the changes for tourist visas would take place.
Americans have been staying away from Venezuela as crime has soared, exchange rates have become difficult to navigate and Maduro has stepped up attacks on the U.S. government. Only 36,000 U.S. citizens visited in the first nine months of 2014, about half the number that visited two years earlier, according to Venezuela Tourism Ministry data. Overall, some 950,000 foreigners visited Venezuela last year.
The move could have a bigger impact on business travelers than holiday beach-goers. As one of the world's largest oil producers, Venezuela remains an important destination for executives, and the new restrictions could affect U.S. companies investing here.
Earlier in the day, Venezuelans took to the streets of Caracas in dueling demonstrations, with one group calling attention to a crackdown on government opponents and another showing support for the embattled socialist administration.
Government supporters marched to the presidential palace to commemorate the anniversary of a convulsion of violence in Caracas known as the "Caracazo."
In 1989, police fired indiscriminately on people demonstrating against austerity measures, killing hundreds. The event is widely seen by government backers as evidence of the brutality of the administrations that preceded the revolutionary government launched 16 years ago by the late President Hugo Chavez.
Opposition activists, meanwhile, gathered to denounce the Feb. 19 arrest of Caracas Mayor Antonio Ledezma and the death on Tuesday of a teenager who was shot during an anti-government protest.
The protesters demanded that authorities release Ledezma, who is being held on charges of conspiring in what Maduro has called a U.S.-backed coup plot.
As evidence against Ledezma, Maduro's administration pointed to the mayor's signature on an opposition document calling for a "national transition." On Saturday, opposition leaders urged Caracas residents to sign the document, saying the government can't arrest the whole city.
The administration has opened cases against 33 of the country's 50 opposition mayors, according to the Venezuelan Mayors Association.
In San Cristobal, where the 14-year-old was fatally shot this week during an anti-government protest, thousands of people massed in the streets of the Andean town known for sparking the country's protest movements. Hard-line opposition leader Maria Corina Machado was among the marchers wearing T-shirts printed with an image of the slain boy's face.