The Lebanese army command confirmed Thursday that officer Samer Hana was killed when his helicoper came under fire from unknown militants and crashed on landing in southern Lebanon.

"Officer Samer Hana was killed when his helicopter was fired at, from militants in the area of Iqlim al Tuffah," said a Lebanese army statement.

"The gunfire forced the helicopter to make an emergency landing causing the death of Hana," the statement said, adding that the army was investigating the incident.

Unconfirmed reports said that three others on board the helicopter were injured.

Witnesses in Iqlim al Tuffah said they heard gunfire before the helicopter made its emergency landing in the area of the hills of Sujed.

Lebanon's militant Hezbollah movement in a statement denied firing at the helicopter and said "our command was aware the Lebanese army was conducting three-day manoeuvres in the area."

Initial reports said the helicopter was passing over an area where Lebanese soldiers and United Nations Interim Force in Southern Lebanon (UNIFIL) peacekeepers were conducting manoeuvres near Sujed, Iqlim al Tuffah, east of the southern port city of Sidon.

However, UNIFIL sources told dpa that "the area where the crash took place is not within their line of duties and that there were no joint manoeuvres in the area."

Earlier this month, 10 Lebanese soldiers were among the 15 people killed in a bomb attack in the northern city of Tripoli. No one has claimed responsibility for the attack.

Last year, the Lebanese army crushed a fundamentalist militant group believed linked with the al-Qaeda terrorist network in northern Lebanon. The army has since been the target of several attacks in the region of Tripoli.

Fatah al-Islam first emerged in November 2006, declaring that it had split from Fatah al-Intifada, a pro-Syrian Palestinian faction based in Beirut. The Lebanese government claims that the group is run by Syrian military intelligence and that its purpose is to cause instability in Lebanon.

The Lebanese army engaged for three months in fierce fighting with the group who were holed inside the Palestinian camp of Nahr al-Bared before managing in September 2007 to crush Fatah al-Islam, killing most of its members and arresting the rest.

But its leader Shaker Al Abssi managed to escape along with some 30 others. A statement by the group a month later threatened to avenge the killing of its members by the Lebanese army.