Lebanon’s president has agreed to invite US envoy Amos Hochstein to Beirut to continue negotiations over the demarcation of its southern maritime border with Israel, the office of the Lebanese caretaker prime minister said on Monday.

Lebanon warned Israel on Sunday against any “aggressive action” in disputed waters where both states hope to develop offshore energy, after a ship operated by London-based Energean arrived off the coast to produce gas for Israel.

President Michel Aoun said any activity in the disputed area would amount to an act of aggression and a provocation, after the arrival of the natural gas storage and production ship operated by London-based Energean.

Israel says the field in question is within its exclusive economic zone, not in disputed waters.

But in a statement, the Lebanese presidency said Aoun discussed with caretaker Prime Minister Najib Mikati the vessel’s entry “into the disputed maritime area with Israel, and asked the Army Command to provide him with accurate and official data to build upon the matter.”

Aoun said negotiations to delineate the southern maritime border continued and “any action or activity in the disputed area represents a provocation and an aggressive action.”