"The army's anti-aircraft guns fired at four enemy Israeli planes that had been overflying the (southern) area of Marjayoun this morning," an army spokesman said, on condition of anonymity.
An AFP correspondent in southern Lebanon said about 70 rounds had targeted four Israeli planes.
While Lebanon's army publishes almost daily reports of Israeli violations of Lebanese air space, the military rarely opens fire unless the planes fly within range of its guns.
The Israeli infringements are a breach of UN Security Council Resolution 1701 which ended the devastating 2006 war between Israel and Lebanon's Shiite militant group Hezbollah.
Israel argues that the overflights are necessary to monitor what it says is massive arms smuggling by Hezbollah in breach of the same resolution.
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