BEIRUT: Lebanon warned the United Nations on Monday that Israel's proposed sea border threatens peace and security, as tensions rise between the neighbours over offshore oil and gas reserves.

In a letter sent to secretary-general Ban Ki-moon, which was drafted and mistakenly leaked to the media in August, Foreign Minister Adnan Mansour argues that the geographic coordinates that Israel submitted to the U.N. demarcating its maritime borders violate Lebanon’s sovereignty and economic rights

“[Israel’s demarcation violates Lebanon’s] regional waters and economic zone and misappropriates around 860 square kilometers, consequently placing international peace and security in danger,” Mansour said in his letter.

“[Mansour] asks the secretary-general of the United Nations to take all measures it deems appropriate to avoid any conflict,” the letter said.

In July, the head of Parliament’s Public Works, Transport, Energy and Water Committee said Lebanon might be forced to file a complaint against Israel to the U.N. Security Council under its Chapter 7, which sets out the council’s powers to maintain peace.

Israel and Lebanon both lay claim to a disputed area that spans some 860 square kilometers off the coast between the two countries and is said to be rich in gas and oil resources.

In July Israel’s Cabinet approved a map of its proposed maritime borders, which Lebanon at the time labeled an “aggression” against its gas and oil rights.

Lebanon’s Parliament approved a draft law demarcating maritime borders with Israel earlier this year, following its proposal to the U.N. in 2010 which included the 850-square-kilometer economic zone.

In June, Lebanon filed a complaint to the U.N. over an agreement made between Cyprus and Israel demarcating an Exclusive Economic Zone at the maritime border between the two countries.

The dispute over the maritime area has worsened an already tense relationship between Lebanon and Israel. Last month, Hezbollah threatened the Jewish State against any attempt to encroach on Lebanon’s resource-rich territorial waters.