The Lebanese military said Wednesday that Israeli warplanes have sharply increased their activity over Lebanon in the past week, including at least 12 sorties in less than 24 hours in the country's south.

The flights come amid Israeli concerns about the civil war in neighboring Syria and fears that advanced weapons could reach hostile groups in Syria or the militant anti-Israel Hezbollah group in Lebanon.

Among Israeli security officials' chief fears is that Hezbollah could get its hands on Syrian chemical arms and SA-17 anti-aircraft missiles. If that were to happen, it would change the balance of power in the region and greatly hinder Israel's ability to conduct air sorties in Lebanon.

Israel believes that Damascus obtained a battery of SA-17s from Russia after an alleged Israeli airstrike in 2007 that destroyed an unfinished Syrian nuclear reactor.

Earlier this week, Israel moved a battery of its new "Iron Dome" rocket defense system to the northern city of Haifa, which was battered by Hezbollah rocket fire in the 2006 Israel-Hezbollah war. The Israeli army called that move "routine."

A Lebanese army statement said the last of the sorties took place at 2 a.m. local time Wednesday. It said four warplanes which flew in over the southernmost coastal town of Naqoura hovered for several hours over villages in southern Lebanon before leaving Lebanese airspace.

It said similar flights by eight other warplanes were conducted Tuesday.

There was no immediate comment from Israel.

A Lebanese security official said the flights were part of "increased activity" in the past week but did not elaborate. He spoke on condition of anonymity because he was not authorized to brief the media.

The area of Lebanon where the flights took place borders southern Syria.

Israeli violations of Lebanese airspace are not uncommon and Lebanese authorities routinely lodge complaints at the U.N. against the flights.