WASHINGTON, Nov 22 (Reuters) - Five of six executives of U.S.-based refiner Citgo who were arrested in Caracas this week are U.S. citizens, according to a source familiar with the matter, a possible complication in Venezuela’s growing sweep of corruption in the oil industry.

Military intelligence agents detained the Texas-based executives during an event at state oil company PDVSA’s headquarters in Caracas on Tuesday, two sources told Reuters, in the latest of dozens of high-level arrests over the last few months.

Five of the arrested executives are dual citizens of Venezuela and the United States: Tomeu Vadell, vice president of refining operations; Alirio Zambrano, vice president and general manager of Corpus Christi refinery; Jose Luis Zambrano, vice president of shared services; Gustavo Cardenas, vice president of strategic shareholder relations, government and public affairs; Jorge Toledo, vice president of supply and marketing.

The sixth, acting Citgo president, Jose Pereira, has Venezuelan citizenship and U.S. permanent residency, the source said.

Venezuela’s Information Ministry, PDVSA, and Citgo did not respond to requests for comment. The White House declined to comment and referred queries to the State Department.

An official at the State Department said they had seen reports on the detention of U.S. citizens in Venezuela but declined to comment on names or details of those arrested, citing “privacy considerations.”

“Venezuela is required under the Vienna Convention on Consular Relations to provide consular notification to the U.S. upon request of a detained U.S. citizen, and to provide consular access. When a U.S. citizen is arrested overseas, we immediately request permission to visit him or her,” the official said.

State Prosecutor Tarek Saab has declared a “crusade” against “organized crime” within PDVSA, and has now arrested around 50 oil managers since taking office in August.

Opposition leaders say PDVSA has been crippled by malfeasance under 18 years of socialist rule. They attribute the arrests to in-fighting among rival government factions rather than a genuine desire to root out corruption.

Sources close to PDVSA also said the arrests owe more to turf wars for control of the company, which is the financial motor of Venezuela’s ailing economy.