A Lebanese security source claimed late on Tuesday that a Lebanese army colonel suspected of spying for Israel fled to the Jewish state last week, Reuters reported. Lebanon has registered a formal complaint with the United Nations about its findings, saying the alleged espionage is in breach of the Security Council resolution that put an end to the 2006 conflict. There has been no official word from Israel. In a regular report on Lebanon for the United Nations Security Council, issued on Tuesday, UN Secretary-General Ban Ki-moon said he was concerned about the Lebanese allegations of the Israeli spy-ring. The allegations, "if proved, could endanger the fragile cessation of hostilities that exists between Israel and Lebanon," Ban wrote. Ban went on to call on Israel and Lebanon to seek a permanent cease-fire in order to shore up their fragile peace, urging Lebanon to secure its border with Syria and saying Israel must complete its withdrawal from all land north of the so-called Blue Line, which separates Israeli and Lebanese forces. The wave of detentions in Lebanon began in April with the arrest of a former brigadier general of the General Security directorate. Two other Lebanese army colonels have been detained in a probe into spying for Israel that has led to more than 50 arrests. Lebanese authorities have described the arrests as a major blow to Israel's intelligence-gathering in the country. Hizbullah leader Hassan Nasrallah has called for the execution of those convicted. Lebanese security officials have said at least one of the suspects was involved in the 2004 assassination of Hizbullah commander Ghalib Awali. Awali was killed in an explosion in Beirut's southern suburbs.