By Ellen Francis
BEIRUT (Reuters) - Lebanon's three top leaders accused Israel on Tuesday of threatening the stability of the border region between the two countries, where calm has largely prevailed since a 2006 war, amid rising tension over territorial and maritime boundaries.
President Michel Aoun, Prime Minister Saad al-Hariri, and Parliament Speaker Nabih Berri agreed to act to prevent Israel from building a wall on Lebanese land at the frontier, and threatening an offshore energy block in disputed waters.
Israel says the wall is being built on its territory.
Arguments over the wall and Lebanon's plans to explore for offshore oil and gas in the disputed maritime waters have elevated tensions between Israel and Lebanon, which is home to the powerful Iran-backed Shi'ite group Hezbollah.
The Lebanese-Israeli border has been calm since the month-long war of 2006 between Israel and Hezbollah which killed around 1,200 people in Lebanon, mostly civilians, and 160 Israelis, most of them troops.
Israel says the wall it is building is on Israeli sovereign land. The Lebanese government says it passes through territory that belongs to Lebanon but which lies on the Israeli side of the Blue Line, where the U.N. demarcated Israel's withdrawal from southern Lebanon in 2000.
The three leaders met to study the recent "Israeli threats, and saw in them ... a direct threat to the stability" of the border region, the president's office said in a statement.
They agreed to take measures "at various regional and international levels to prevent Israel from building the cement wall...and from the possibility of infringing on Lebanon's oil and gas wealth and its (territorial) waters," it said.
Last week, Israeli Defence Minister Avigdor Lieberman called Lebanon's first offshore oil and gas exploration tender "very provocative" and urged international firms not to participate.
Lebanon has an unresolved maritime border dispute with Israel over a triangular area of sea of around 860 sq km (330 square miles). The zone extends along the edge of three of five energy blocks that Lebanon put to tender early last year.
Lebanon in December approved a bid by a consortium of France's Total TOTF.PA, Italy's Eni ENI.MI and Russia's Novatek NVTK.MM for two blocks.
(Reporting by Ellen Francis; Editing by Tom Perry, William Maclean)