BEIRUT, Lebanon - Lebanese troops opened fire Thursday on Israeli warplanes flying low over southern Lebanon but no hits were reported, Lebanese officials said.

Soldiers opened up with machine-guns and light anti-aircraft weapons mounted on armoured vehicles at two planes that flew by just east of Marjayoun town near the border at midmorning, a Lebanese security official said.

An army statement issued later in the day said "the Lebanese army's ground anti-aircraft guns confronted the hostile Israeli aircraft during its violation of Lebanese airspace over the regions of Marjayoun and Bint Jbeil, forcing it to leave over the town of Alma Chaab in the direction of the occupied lands.''

Lebanon, like most Arab countries, does not recognize Israel.

A total of 150 rounds were fired, an official said, speaking on condition of anonymity prior to the formal announcement.

The volleys of anti-aircraft fire caused panic among some of the 100 students at a middle school in Marjayoun, with girls screaming and crying.

One of the Lebanese soldiers from a nearby base burst into the school, telling teachers that it was the army that was the firing, according to witnesses at the school. Students were sent home about two hours before they usually break, they said.

The Israeli military does not comment on air operations, but there were no reports from Jerusalem of any planes being hit.

Israeli warplanes frequently fly over Lebanese airspace in what Israel says are reconnaissance missions, but this was the first time the Lebanese army has fired on the aircraft since an Aug. 14, 2006, ceasefire ended a month-long war between Israeli and Hezbollah guerrillas.

Earlier this year, Lebanese and Israeli soldiers briefly exchanged fire near the border village of Maroun el-Rass where the UN-demarcated Blue Line was not clearly marked. There were no casualties.

Israeli overflights have been a constant source of tension between the two countries. Before last year's war, Hezbollah used to open fire on Israeli planes, with shrapnel from the anti-aircraft fire falling on Israeli communities across the border, causing some casualties.

The deployment of about 15,000 Lebanese troops in the south along with some 13,000 UN peacekeepers after the UN-brokered ceasefire has not stopped the flyovers despite the UN describing them as a violation of Lebanese sovereignty.

Lebanon has reported an increasing number of overflights in recent days and the shooting on the planes Thursday signalled the country's growing impatience with the Israelis and the inability of the United Nations to prevent such flights.

Asked to comment on Thursday's incident, Ari Gaitanis, a spokeman for the UN Interim Force in Lebanon, said Israeli flights over Lebanon "constitute repeated violations of Security Council resolutions, and also damage efforts to reduce tension and stabilize the situation in southern Lebanon.''

He said the UNIFIL commander and senior UN representatives in the region as well as a number of interested member states "have voiced concern and called on Israel to cease these air violations.''

"We regularly report to the Security Council about all the violations. At the same time we urge all parties to act with restraint in order to avoid any escalation of the situation,'' Gaitanis told The Associated Press.