BEIRUT Lebanon accused Israel on Monday of breaking international law by allowing energy firms to explore for offshore gas in the absence of an agreement between the two countries on their maritime border.
Foreign Minister Ali al-Shami said no company should be allowed to operate in waters off the two neighbors, which remain in a formal state of war, until their territorial waters were internationally recognized.
Texas-based Noble Energy and its Israeli partners say they have made the world's biggest gas discovery of the decade in the Leviathan prospect, 130 km (80 miles) off the Israeli port of Haifa. Another field, Tamar, is due to start production by 2013.
Lebanon, which says that seismic surveys have identified promising quantities of natural gas in its own waters, appealed to United Nations Secretary-General Ban Ki-moon last week to ensure Israeli exploration did not encroach on its waters.
"Israel, through international companies, is violating Lebanon's maritime borders," Shami told Reuters in an interview. "We will confront any violation and infringement of Lebanese sovereignty, not just through legal channels but through all internationally legitimate means."
Israel has said the gas discoveries fall within its own economic waters, but Shami said studies showed that some Mediterranean gas fields could be shared between Israel, Lebanon and Cyprus. He also said, without giving details, that maps showed that Israel was violating Lebanese waters.
Last year Lebanon said it submitted maps and coordinates to the United Nations to support its territorial claims.
"Israel has started to operate outside international law and outside the treaty of the law of the sea," Shami said, referring to a U.N. convention governing use of seas and oceans which he said Lebanon had ratified but which Israel has not signed.
"No company should proceed (with exploration) before there is recognition from (the United Nations) on the issue of the borders of the exclusive economic zone," he said.
Prime Minister Saad al-Hariri pressed U.N. chief Ban on the issue during talks in New York on Sunday, Hariri's office said, and Shami met U.N. Special Coordinator for Lebanon Michael Williams on Monday to ask for help marking out the sea border.
Ban's spokesman said United Nations Resolution 1701, which halted hostilities in the 2006 war between Israel and Lebanon's Hezbollah, did not cover delineating Lebanon's maritime border.
But Williams, speaking after meetings with Shami and other politicians, said the United Nations might play a role.
"We have to discuss it with the U.N.'s lawyers in New York," Williams said in remarks published by his office.
"Regarding the delimitation of the borders, normally this requires the agreement of all parties. But this is something that is obviously difficult in the case of Lebanon's maritime border with Israel."
Lebanese officials have told Reuters privately that the U.N. had assured Beirut it was working on a solution that could respond to Beirut's request for help in demarcation, though U.N. officials in New York were skeptical about the world body's options.
Spurred on by Israel's plans to drill for gas, Lebanon's parliament ratified a long-awaited energy law last August which paves the way for exploration of its own offshore reserves.
But it still has a long way to go to catch up with Israel. It has to identify blocs, supply data to interested investors, select bidders and have companies start exploration work, while the Israelis already have firms drilling for gas.
(Additional reporting by Louis Charbonneau at the United Nations; Editing by Mark Trevelyan)