Lebanon's President Michel Aoun Thursday demanded Israel halt all exploration in an offshore gas field on its southern border, as part of an ongoing dispute over their shared sea frontier.
The countries, which are still technically at war, last year took part in indirect US-brokered talks to discuss demarcation to clear the way for offshore oil and gas exploration.
But those talks stalled after Lebanon demanded a larger area, including part of the Karish gas field, where Israel has given a Greek firm rights for exploration.
"Lebanon is within its rights to evolve its position," Aoun told visiting US envoy David Hale, asking for "international experts" to weigh in on the issue.
He called for a "commitment to not carrying out any oil or gas activities and not starting any exploration in the Karish field and its adjacent waters" until the matter was settled, the presidency said.
The talks last year were supposed to discuss a Lebanese demand for 860 square kilometres (330 square miles) of territory in the disputed maritime area, according to a map sent to the UN in 2011.
But Lebanon then said the map was based on erroneous calculations and demanded 1,430 square kilometres (552 square miles) more territory further south, including part of Karish.
Lebanon's outgoing public works minister this week signed a draft decree cementing Lebanon's demand for the larger area.
Aoun, the caretaker prime minister and the outgoing defence minister still have to sign it before Lebanon sends it to the UN to make its new demand official.
For his part, Hale on Thursday said the US was ready to continue brokering Israel-Lebanon talks "on the basis on which we initiated these discussions", appearing to reject the Lebanese move towards demanding a larger area.
The US envoy's visit comes as Lebanon's top politicians have for months argued over the composition a new cabinet to launch reforms and unlock financial aid to lift the country out of its worst economic collapse in decades.
"The time to build a government, not block it, is now," Hale said.
"Those who continue to obstruct progress on the reform agenda jeopardise their relationship with the United States and our partners and open themselves up to punitive actions."
The US in November slapped sanctions on Aoun's son-in-law, former energy and foreign affairs minister Gebran Bassil, for alleged corruption.
It also sanctioned former finance minister Ali Hassan Khalil and former transport minister Yusef Fenianos in September for alleged graft and support of the Iran-backed Hezbollah movement.
Hezbollah is black-listed by Washington, but it is also a powerful political player in Lebanon with seats in parliament.
Lebanon's government stepped down after a massive blast at Beirut's port in August 2020, but deeply divided politicians have been unable to form a new cabinet ever since.