A Lebanese military officer has been killed after armed men brought down a Lebanese army helicopter flying over the southern village of Sejoud, military officials have said.

Lebanese soldiers and Hezbollah members cordoned off the area in the Telal Sejoud region on Thursday and stopped journalists from approaching the crash scene.

Al Jazeera's Zeina Khodr, in Beirut, said the helicopter was fired at and "forced to make an emergency landing".

"The army has said it was on a training mission in an area ... outside of that patrolled by UN forces."

The Telal Sejoud area lies in Iqlim al-Touffah district, mountainous ridge around 20km north of the Israeli border where UN peacekeepers have a mandate to operate.

Investigation launched

Lebanese military officials identified the dead officer as  Samer Hanna, a first  lieutenant, and said an investigation into the incident had been launched.

The area was considered a Hezbollah stronghold during the Israeli occupation of southern Lebanon and witnessed fierce battles before Israel's withdrawal in 2000.

As part of the ceasefire deal that ended the devastating 2006 war between Hezbollah and Israel, the army deployed in southern Lebanon along with a strengthened United Nations peacekeeping force.

Nine Lebanese soldiers and five civilians were killed in a bombing at a bus stop in the northern port city of Tripoli earlier this month in an attack thought to have been aimed at the army.