GUYANA President Irfaan Ali slammed an incursion by an armed Venezuelan naval vessel on Saturday into disputed waters that are home to a mammoth offshore oil deposit being developed by ExxonMobil.

In a televised address, Mr Ali said Guyana was hurriedly notifying all of its international allies and had summoned Venezuela’s ambassador to lodge a formal protest.

“This incursion is a matter of grave concern,” he said. 

“Guyana’s maritime boundaries are recognised under international law.”

Venezuelan Vice-President Delcy Rodriguez disputed Mr Ali’s claims and called ExxonMobil’s oil installations “illegal.”

“He’s telling bald-faced lies,” she said in a statement.

Since ExxonMobil made its major oil discovery in Guyana in 2015, Venezuela has revived a century-old territorial dispute with Guyana and held a referendum promoting its claim to the Essequibo region, which comprises about two thirds of Guyana’s land mass.

The area was colonised by Britain for more than a century, and it has been under Guyanese control since 1966, when the nation gained independence.