Georgetown (Guyana) (AFP) - Guyana warned Monday it would "vigorously" resist any attempt by Venezuela to enforce a new claim over coastal waters where Exxon Mobil recently announced an important oil find.

Caracas issued a decree May 27 laying claim to waters off the Essequibo, a disputed territory that borders Venezuela and encompasses more than half of Guyana.

The Venezuelan action came less than a month after Exxon Mobil said it had made a "significant" discovery in an offshore concession granted by Guyana.

Guyana's foreign ministry charged that the Venezuelan decree was a violation of international law and a threat to regional peace and security.

"Any attempt by the Bolivarian Republic of Venezuela to apply that instrument in an extra-territorial manner will be vigorously resisted by the Cooperative Republic of Guyana," the foreign ministry statement said.

The statement stressed that Guyana would continue to access and develop its offshore natural resources.

Guyana, a former British colony, maintains that the land boundary was settled in 1899 by a court of arbitration set up after a crisis that prompted the United States to intervene in favor of Venezuela against Britain, asserting the Monroe Doctrine.

Venezuela has never recognized the line, and the dispute has simmered ever since, extending in recent years to maritime rights off the disputed area.

In 2013, Venezuela's navy intercepted a Malaysian-owned oil exploration vessel in an offshore concession that Guyana granted to the Texas, US-based oil company, Anadarko Petroleum Corporation.