Lebanese security officials say gunmen opened fire on an army helicopter flying over southern Lebanon, killing a soldier.

The officials say the helicopter was on a training mission Thursday when it came under fire and was forced to make an emergency landing in the village of Sejoud.

It is not clear who fired on the helicopter.  The area where the attack occurred is a stronghold of the Islamic militant group Hezbollah.

The Lebanese army deployed in the southern region, along with a reinforced U.N. peacekeeping force, after Israel's war with Hezbollah in 2006.

On Wednesday, the U.N. Security Council extended the mandate of the 13,000 strong U.N. peacekeeping force (UNIFIL) in southern Lebanon by another year.  Council members also urged all parties to respect a U.N. ceasefire resolution that ended the Israel-Hezbollah war.

Israel's U.N. Ambassador Daniel Carmon says Hezbollah is violating the cease-fire by deploying armed fighters in southern Lebanon.  He also says Iran and Syria continue to send weapons to Hezbollah over the Lebanese border in defiance of the truce.

A team of U.N. security experts issued a report this week saying Lebanon's government has not done enough to secure its borders to prevent arms smuggling.

Lebanon's U.N. envoy Nawaf Salam says Israel is violating the cease-fire by continuing infringements of Lebanese airspace.  He also says Israel has ignored obligations to hand over maps of cluster bombs it dropped on Lebanon in the 2006 war. 

Some information for this report was provided by AFP, AP and Reuters.