CARACAS, Venezuela, (AFP) – Venezuela lashed out at the United States (US) after a senior official supported Guyana in a simmering territorial dispute with its South American neighbour in an area where a US company extracts oil.

President Nicolas Maduro accused Washington of “insolent meddling” after Brian Nichols, the assistant secretary of state for Western Hemisphere affairs, supported Guyana’s “sovereign right to develop its own natural resources.”

Writing on X, the former Twitter, Nichols said “efforts to infringe upon Guyana’s sovereignty are unacceptable. We call on Venezuela to respect international law.”

The latest chapter in a decades-old territorial quarrel was triggered by Guyana auctioning off oil blocks in a disputed region that Caracas claims as part of its territory.

Venezuela has long argued that the 160,000-square-kilometre (62,000-square-mile) region of Essequibo, administered by Guyana, should fall within its borders.

A former Dutch and British colony, Guyana claims its border with Venezuela was fixed by an arbitration tribunal in 1899.

But Venezuela says the Essequibo river to the east of the region forms a natural border between the two countries, recognized since 1777 until the arbitration ruling, which it rejects.

The row intensified after US oil giant ExxonMobil discovered crude oil deposits off the region’s coast in 2015.

A dispute is pending before the International Court of Justice (ICJ) in The Hague at Guyana’s request, and despite objections from Venezuela.

“We firmly reject the insolent meddling of the United States,” said Maduro of the Nichols statement.

The Venezuelan foreign ministry in a statement said the United States was “fostering a dangerous escalation to a controversy that has been addressed through diplomatic and peaceful mechanisms for years.”

Georgetown said Tuesday it “reserves the right to pursue economic development activities in any portion of its sovereign territory.”