By Mathew Cohen Venezuela's coast guard vessels allegedly entered Guyanese waters on March 1, approaching an ExxonMobil production vessel in the disputed offshore region, Guyana's President Irfaan Ali has announced.

Venezuelan coast guard vessels entered Guyana’s waters near Exxon Mobil Corp.’s offshore drilling site over the weekend and transmitted a radio message claiming it was patrolling a “disputed international” maritime zone.

GEORGETOWN, Guyana (AFP) — The United States on Saturday denounced what it said were Venezuelan naval vessels “threatening” an ExxonMobil unit in maritime territory claimed by Guyana.

Guyanese President Irfaan Ali said on Saturday that a Venezuelan coast guard patrol entered Guyanese waters earlier in the day, approaching an output vessel in an offshore oil block managed by Exxon Mobil .

Guyana and Venezuela clashed again after the former complained of incursion into its oil-rich maritime territory, which then triggered a warning from Caracas against “dangerous provocation” based on “lies”.

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.

The United States issued a stern warning to the Nicolás Maduro regime on Saturday following reports that a Venezuelan patrol boat entered into Guyanaese waters, threatening ExxonMobil’s offshore operations.