In a live broadcast on state television, Maduro said the man was arrested on Thursday in the northwest state of Falcon where he was spying on the Amuay and Cardon oil refineries.
They captured “a marine, who was serving as a marine on CIA bases in Iraq,” Maduro said. “He was captured with specialized weapons, he was captured with large amounts of cash, large amounts of dollars and other items.”
Maduro did not give further details, but said the detainee was giving a statement in custody.
Neither the US State Department nor the White House immediately responded to requests for comment.
Amuay and Cardon make up the Paraguana Refining Center, which has a nominal processing capacity of 971,000 barrels per day. Both have experienced multiple outages in recent years that the opposition blames on mismanagement and lack of maintenance.
Word of the alleged US spy came after a Venezuelan court last month sentenced two former US Green Berets to 20 years in prison for their role in a failed incursion in May.
Separately during Friday’s broadcast, Maduro said that in recent days security forces had also foiled a plot to cause an explosion at another oil refinery, El Palito in Carabobo state.
He did not elaborate.
Hit by US sanctions that have exacerbated acute fuel shortages, the government on Friday announced a new fuel distribution initiative and said it was planning new refining projects, without providing further details.