Guyana’s president has denounced an incursion by an armed Venezuelan naval vessel in disputed waters and home to a mammoth offshore oil deposit being developed by ExxonMobil

A diplomatic spat is brewing after Venezuelan naval vessels entered ExxonMobil’s Stabroek block offshore Guyana, reportedly threatening its floating production, storage and offloading vessels operating there including the Prosperity FPSO amid an escalating territorial dispute between the two nations.

The South American neighbours are involved in a long-running dispute about which country owns the oil-rich Essequibo area.

Guyana’s government said Saturday that a Venezuelan naval patrol ship entered its waters and approached a vessel contracted by Exxon Mobil (NYSE:XOM) in the Straboek block, according to media reports.