Venezuelan authorities say they have arrested three US citizens, two Spaniards and one Czech citizen suspected of plotting to destabilise the country.

Interior Minister Diosdado Cabello said hundreds of weapons had also been seized, and that the detainees were plotting to assassinate Venezuelan President Nicolás Maduro and other top officials.

It comes two days after Washington sanctioned 16 Venezuelan officials who are closely aligned with President Maduro, following his disputed election victory.

The Venezuelan government said the Spaniards detained were linked to Madrid’s National Intelligence Centre (CNI). However, Spanish government sources have told local media the two do not belong to the intelligence organisation.

In a news conference on Saturday Cabello said: “The CIA is leading this operation, and that does not surprise us but they, the National Intelligence Centre of Spain, have always maintained a low profile knowing that the CIA operates in this area.

“These two detainees even tell us about a group of mercenaries they are looking for to bring to Venezuela with very clear objectives to assassinate President Nicolas Maduro, Vice President Delcy Rodriguez, myself, and another group of comrades who are leading our party and our revolution.”

The US has rejected the accusations.

“Any claims of US involvement in a plot to overthrow Maduro are categorically false,” according to the State Department, who says Washington “continues to support a democratic solution to the political crisis in Venezuela”.

The arrests come amid a feud between the Maduro government and the US and Spain.

Cabello said the Spaniards were detained in Puerto Ayacucho, south of the capital Caracas.

Spanish authorities have requested more information from Venezuela, with the Spanish embassy requesting access to those detained.

“They contacted French mercenaries, they contacted mercenaries from eastern Europe and they are in an operation to try to attack our country,” Cabello said, adding that 400 firearms were confiscated in the operation.

On Friday, Venezuelan Foreign Minister Yván Gil summoned Spain’s ambassador in Caracas to protest at a minister’s description of the Venezuelan government as a “dictatorship”, after days of mounting bilateral tensions.

On Thursday, the US Treasury said it was targeting “key officials involved in Maduro’s fraudulent and illegitimate claims of victory and his brutal crackdown on free expression following the election”.

Maduro was declared the winner of July’s presidential election by Venezuela’s National Electoral Council (CNE), which is closely aligned with the government.

But the CNE has not published any detailed voting tallies supporting a Maduro victory. Data published by the opposition suggests its candidate, Edmundo González, won instead.