Hundreds of people and several lawmakers protested on Saturday in southern Lebanon against Israel moving a gas production vessel into an offshore field partly claimed by Beirut.
The demonstration comes just days before the US envoy mediating maritime border talks between the two neighbours is expected in Lebanon, and after the ship operated by London-listed Energean Plc arrived in the Karish gas field last week.
Several hundred people waved Lebanese and Palestinian flags at Lebanon's border town of Naqoura to protest Israel's claim on the area where the Karish field is located, an AFP correspondent said.
"We absolutely refuse to neglect Lebanon's maritime resources, which belong to all Lebanese," said lawmaker Firas Hamdan, reading a joint statement from 13 independent parliamentarians, most of whom were newly elected last month.
Lebanon and Israel have no diplomatic relations and are separated by a UN-patrolled border.
Lebanon's president and prime minister have condemned Israel for moving the vessel into the Karish field, and have invited US envoy Amos Hochstein to Beirut for mediation.
Hochstein is scheduled to arrive in Lebanon on Monday for a two-day visit, according to the US State Department.
Lebanon's powerful Iran-backed Hezbollah group this week warned Energean against proceeding with its activities.
Israel and Lebanon have fought over how exactly to demarcate their maritime border for well over a decade.
Lebanon’s offshore oil and gas reserves alone are estimated to be valued at around $250 billion, or about eight times Lebanon’s GDP in 2020.
Lebanon and Israel disagree over where their shared border lies, as a difference of a few hundred square kilometres could mean billions in lost fuel.