A spokesperson for the US State Department said "a US military member" had been detained in Venezuela and that it was aware of unconfirmed reports of two additional US citizens being detained there, but rejected a Venezuelan claim of US involvement in any plot to overthrow the government.
The Venezuelan announcement is likely to deepen the country's already substantial tensions with Spain and the United States after Venezuela's disputed presidential election in July.
Venezuelan Interior Minister Diosdado Cabello in a press conference said two Spaniards were allegedly linked to Spain's secret service and planning the assassination of a mayor.
The US State Department denied an attempt to oust leftist Venezuelan President Nicolas Maduro. (AP PHOTO)
Spanish media reported that Spain's government denied this claim.
Cabello also accused three US citizens and a Czech of involvement in terrorist acts, including alleged plans to assassinate Maduro and other officials.
"These groups seek to seize the country's wealth, and we as a government will respond firmly to any destabilisation attempt," Cabello said. He added that about 400 rifles originating in the United States had been seized.
The State Department said the US was not involved in an attempt to oust leftist Venezuelan President Nicolas Maduro.
"Any claims of US involvement in a plot to overthrow Maduro are categorically false," the spokesperson said. "The United States continues to support a democratic solution to the political crisis in Venezuela."
"We are seeking additional information. We are closely monitoring the situation," the official added, while declining to provide additional details due to privacy considerations.
A Spanish foreign ministry source told Reuters it was asking Venezuela for more information.
"The Spanish embassy has sent a verbal note to the Venezuelan government asking for access to the detained citizens in order to verify their identities and their nationality and in order to know what they are accused of exactly," the source said, speaking on condition of anonymity.
The Spanish nationals were detained while taking photographs in the town of Puerto Ayacucho, Cabello said.
"These citizens have links - we know they will say no, that it is a lie - they have links with the center," Cabello said, referring to Spain's intelligence arm.
"Spain will decide what to do, if it is going to keep meddling in Venezuela's affairs."
Venezuela recalled its ambassador to Spain this week for consultations and summoned the Spanish ambassador to appear at the foreign ministry after a Spanish minister accused Maduro of running a "dictatorship," escalating diplomatic tensions following a disputed presidential election.
Venezuela was also angered by the decision of Spanish Prime Minister Pedro Sanchez to meet with Venezuelan opposition candidate Edmundo Gonzalez Urrutia, who went into exile in Spain last week after being threatened with arrest by Maduro's regime.
