A leading Lebanese politician who is sanctioned by the United States said on Thursday he played a behind-the-scenes role in U.S.-brokered talks to delineate Lebanon's maritime boundary with Israel by liaising with Hezbollah.

Gebran Bassil, a Christian member of parliament and former minister, was sanctioned in 2020 for alleged corruption and material support to Hezbollah but denies the accusations.

He told Reuters in an exclusive interview on Thursday that despite the sanctions, he was personally involved in U.S.-mediated negotiations to draw the sea border between Lebanon and Israel.

"It's only normal that I have a role. Everybody knows this - it's my obligation and it's my duty," he said in his office on the outskirts of Beirut.

"I can link politically with the parties inside and outside... and clearly, we succeeded."

If finalised, the maritime border agreement - hailed by all three parties as a historic achievement - would mark a diplomatic departure from decades of war and hostility as well as opening the door to offshore energy exploration.

Bassil declined to say specifically what kind of role he played, but did say he was in touch with Hezbollah, the powerful armed Iran-backed group that is a sworn enemy of Israel.

"I was in direct and continuous contact with many people – Hezbollah, others than Hezbollah," he said, describing the Iran-backed armed movement's role as "positive."

There was no immediate response from the United States government or from Hezbollah to requests for comment.

Bassil's Free Patriotic Movement is Hezbollah's top Christian ally, and he has credited the armed group for the leverage they offered Lebanon in the negotiations process.

He said his involvement in the file was not an effort to wipe his name of the U.S. blacklist.

"This has nothing to do with the sanctions. Not at all. The sanctions will be removed because they are unfair," he said.

Bassil said he was already undergoing an appeals process in the United States by reaching out to the Treasury Department and demanding details on the U.S. government's file on him through a Freedom of Information Act request.

The American ambassador to Lebanon Dorothy Shea earlier told Reuters that Bassil had not requested sanctions be lifted in exchange for political overtures, including helping secure a maritime border agreement.

"It's not how sanctions work. We're not that cheap," Shea said.

Bassil, a Maronite Christian, is one of Lebanon's most influential politicians and the head of the FPM, which was founded by outgoing President Michel Aoun.