A U.N. envoy said on Tuesday (August 22) it could take the Lebanese army and international troops two to three months to fill a "security vacuum" in southern Lebanon and warned that "unintended" acts could spark renewed fighting. "There is now a security vacuum which the Lebanese Government is trying to fill and the International forces are assisting the Lebanese Government in order to fill that vacuum. I think realistically, up to a point, you will have such a vacuum in Lebanon for the next two, three months", Terje Roed-Larsen, the top U.N. envoy on Syria-Lebanon issues, told Reuters. The U.N. has asked Israel to refrain from using force to prevent Hizbollah guerrillas from rearming, arguing that doing so would constitute a violation of a week-old ceasefire. But Israeli officials say the Jewish state has the right to enforce the arms embargo if no one else will. " So it is a paradoxical situation were there are elements both for optimism but where there are also strong elements for which shows that the situation is still extremely fragile and extremely complicated and extremely dangerous. It's also so unintended incidents can kick off, renewed violence which might escalate and spin out of control", Larsen said. The U.N.-backed truce was jolted by an Israeli commando raid in eastern Lebanon's Bekaa Valley on Saturday, which the United Nations called a violation. The New York-based body says it is also concerned by six Israeli violations of Lebanese air space in the past two days. Israel says Saturday's raid was a defensive action and, as such, does not constitute a breach of U.N. Security Council resolution 1701, which brought the war to an end. It has accused Hizbollah of breaching the resolution by smuggling arms from Syria and has said its jets need to fly over Lebanon to monitor such activities.