By Diego Ore and Brian Ellsworth
CARACAS (Reuters) - Venezuelan President Nicolas Maduro said on Saturday his government had detained U.S. citizens, including a pilot, on suspicion of espionage, in a move likely to strain already tense relations between Washington and Caracas.
Maduro also said his government would order a reduction in the number of U.S. embassy staff in Caracas and prohibit some U.S. officials from entering Venezuela in retaliation for a similar U.S. measure last year. Venezuela would also require U.S. citizens to obtain visas before visiting, he told a rally.
The Venezuelan president, long at odds with Washington, has renewed accusations in recent weeks that the United States is seeking to topple him.
Maduro's political opponents at home call this a smokescreen aimed at distracting from an increasingly severe economic crisis in the oil-exporting nation. Venezuela has been hard hit by the collapse of oil prices over the last nine months.
"We have captured some U.S. citizens in undercover activities, espionage, trying to win over people in towns along the Venezuelan coast," Maduro said at a rally in Caracas adding one was a U.S. pilot detained in the volatile border state of Tachira.
"In Tachira we captured a pilot of a U.S. plane (who is) of Latin origin (carrying) all kinds of documentation," Maduro said, without offering details.
He said U.S. politicians including former President George W. Bush, former Vice President Dick Cheney, and Senator Bob Menendez would be blocked from entering Venezuela.
Menendez in response said: "Being sanctioned by the Maduro regime will never deter me from speaking out against the ruin caused by his government."
A spokesman for the U.S. embassy in Caracas said he was unable to comment, citing a lack of any official diplomatic communication with the Venezuelan government.
An official in U.S. President Barack Obama's administration broadly dismissed the accusations from Caracas.
"The continued allegations that the United States is involved in efforts to destabilize the Venezuelan government are baseless and false," the senior administration official said, speaking on condition of anonymity.
The head of a Venezuelan evangelical organization said on Friday a group of four missionaries had been called in for questioning after taking part in a medical assistance campaign in the coastal town of Ocumare de la Costa.
That pastor, Abdy Pereira, said on Saturday in a telephone interview that the four had left the country for Aruba after having been questioned for several days about alleged involvement in espionage.
"The government attempted to link them to (espionage activities) but there was no evidence that this was the case," said Pereira.
The Communication Ministry did not answer calls seeking details about the identities of the missionaries or their whereabouts.
On the move to reduce the U.S. mission in Caracas, Maduro said he had ordered Foreign Minister Delcy Rodriguez to proceed immediately, based on Vienna convention rules, "to revise, reduce ... and limit the number of officials in the U.S. embassy in Venezuela."
It was not clear when embassy officials would have to leave.
Maduro added that Americans will now need visas to enter Venezuela and will have to pay the same visa fees that Venezuelans pay to get into the United States.
The president's moves followed the arrest this month of Caracas Mayor Antonio Ledezma on conspiracy charges, a move Maduro said would stymie a U.S.-backed coup effort.
Maduro's adversaries said the plot was a charade meant to distract from consumer goods shortages, soaring prices and Maduro's tumbling popularity ratings.
Caracas and Washington have had tense diplomatic relations since the era of late socialist leader Hugo Chavez, who was briefly toppled in a 2002 coup that he said was orchestrated by the State Department.
The government of then U.S. President George W. Bush endorsed that coup before backtracking when Chavez returned to power.
(Reporting by Diego Ore, writing by Brian Ellsworth; Editing by Bernard Orr, Frances Kerry and Michael Perry)