By Neil Marks
BRIDGETOWN, Oct 11 (Reuters) - Guyana's government said on Friday the navy of neighboring Venezuela had evicted a ship used by a U.S. oil exploration company from Guyanese waters, calling the move unprecedented and a serious threat to security.
The Venezuela authorities, meanwhile, accused the survey ship, which was being used by Texas-based Anadarko Petroleum Corp, of violating its territorial waters.
A border dispute has simmered between the two South American countries for more than a century and oil exploration has only fanned the flames.
Guyana's foreign ministry said a Venezuelan naval vessel on Thursday ordered the RV Teknik Perdana to stop surveying and then escorted it to the Venezuelan island of Margarita.
"The actions taken by the Venezuelan navy vessel constitute a serious threat to the peace of this sub-region," Guyana's foreign ministry said in a statement.
"It was...clear the vessel and its crew were not only being escorted out of Guyana's waters, but were under arrest. These actions by the Venezuelan naval vessel are unprecedented."
The Venezuelan government also demanded an explanation.
"Venezuela expresses its profound concern about the way in which foreign vessels, authorized by Guyana's government, barge into Venezuela's territorial waters and exclusive economic zone without permission," Venezuela's foreign ministry said.
Both sides stressed that they wanted a peaceful resolution.
Guyana awarded Anadarko Petroleum Corp a deep-water, exploration license in June last year for a block named Roraima, although details of the concession have not been revealed.
Oil companies have been increasingly interested in the northeastern shoulder of South America since a discovery off nearby French Guyana in 2011 that industry experts described as a game-changer for the region's energy prospects.
Venezuela and Guyana have long argued about the status of the disputed Essequibo region, an area on the border about the size of the U.S. state of Georgia, and over rights to the ocean resources that lie offshore. Venezuela calls it a "reclamation zone," but in practice it functions as Guyanese territory.