The US official mediating a maritime border dispute between Lebanon and Israel said on Monday he remained optimistic about making progress towards a deal and looked forward to returning to the region to make a "final arrangement".
Amos Hochstein made the comments after meeting Lebanon's top leaders as he presses efforts to clinch a rare agreement between enemy states that should allow both to develop offshore resources.
"I remain optimistic that we can make continuous progress as we have over the last several weeks and I look forward to being able to come back to the region to make the final arrangement," Hochstein said.
A senior Lebanese government source said Hochstein had passed on an Israeli proposal that provided Lebanon with "nothing south of Line 23" - a maritime line that was originally Lebanon's demand during negotiations.
Additionally, Israel would allow Lebanon to explore the entire Qana Prospect, an area with the potential to hold hydrocarbons which crosses beyond Line 23.
Lebanon informed Hochstein it was seeking guarantees it could commence exploration in its southern Block 9 in an area already awarded to a consortium led by French oil major Total as soon as an agreement is signed, the source said.
Hochstein told local broadcaster LBCI he expected exploration would move forward in the area once the companies involved had the "legal and diplomatic certainty" that would result from a deal.
Lebanon opposed any Israeli exploration before Lebanon was able to do the same, and informed Hochstein it could not provide guarantees that Israel would be safe from attack if it did so, the source added.
The heavily armed Lebanese group Hezbollah has threatened military action if Lebanon is prevented from exploiting what it deems to be its offshore rights. But it has also said it will respect the decision of the Lebanese government.
In a written statement to Reuters, Israeli Energy Minister Karin El-Harar declined to respond to "media reports."
"The proposal we related last week is serious, and its goal is to bring this issue to a close while preserving Israel's security and energy resilience," the statement said.
A senior Israeli official, speaking to Reuters on condition of anonymity on Sunday, said Hochstein would present a new Israeli proposal that "includes a solution that would allow the Lebanese to develop the gas reserves in the disputed area while preserving Israel's commercial rights".
This would entail "some drilling there" by the Lebanese, the Israeli official said without elaborating.
The United States in 2020 stepped up long-running efforts to mediate an agreement. Tensions over the issue escalated in June as Israel moved towards extracting hydrocarbons while Lebanon's exploration process remained paused.
Prime Minister Najib Mikati gave a thumbs up as he emerged from the meeting on Monday afternoon that also included President Michel Aoun and Parliament Speaker Nabih Berri.
Lebanese deputy parliament speaker Elias Bou Saab said the negotiations were moving "within a short timeframe" and said results could emerge in the next few weeks.
Lebanon and Israel are located in the Levant Basin, where a number of big sub-sea gas fields have been discovered since 2009. Israel already produces and exports gas.