The Ukrainian captain of an oil research ship detained by the Venezuelan navy is being charged with illegally sailing in Venezuela's maritime economic zone — waters that are disputed with neighboring Guyana.

The federal prosecutor's office said Igor Bekirov would appear in a court Monday evening.

The other 35 crew members, including five U.S. citizens, remain in custody. The ship arrived under navy escort Sunday at Margarita Island off Venezuela's Caribbean coast.

The vessel was conducting a seismic study for Texas-based Anadarko Petroleum Corp. under a concession from Guyana. Guyana's government says the ship was well within its territorial waters.

The vessel's seizure threatens to revive a decades-old territorial dispute between Venezuela, South America's biggest oil producer, and Guyana, one of the region's poorest countries.