Beirut - Clashes broke out Saturday between the mainstream Fatah Movement and Jund al-Sham factions at the Ain el-Hilweh Palestinian refugee camp in southern Lebanon, killing at least one person, Palestinian sources said.

Gunmen from both sides fired machineguns and rocket-propelled grenades, forcing many civilians to scurry for shelter, the sources said.

Rival fighters exchanged fire for almost two hours into the evening in the main street in the densely populated camp outside the southern port city of Sidon, a Palestinian official added.

Gunshots were subsequently heard in Sidon itself, with a Fatah leader saying that one person from Fatah was killed.

A Lebanese army spokesman said the fighting was confined to the camp and that troops, positioned at the entrance of the camp and which by longstanding convention do not enter Lebanon's dozen refugee camps, had not got involved.

Jund al-Sham's name refers to the ancient Islamic term of Bilad al-Sham, a region which covers Syria, Lebanon, Jordan, Israel and the Palestinian territories.

Its members are mostly Lebanese, many of whom fought against the army during an Islamist rebellion that broke out on New Year's Eve in 1999 in the predominantly Sunni area of Dinnieh in north Lebanon and left 45 people dead.

The Sunni group also includes Palestinians, mostly dissidents of the fundamentalist Usbat al-Ansar (Band of Supporters), which was outlawed by Lebanese authorities in
1995 for murdering a rival cleric.

Jund al-Sham, which has no clear hierarchy or particular leader, is believed to have about 50 militants armed with assault rifles, mortars and rocket-propelled grenades.

Similar clashes have erupted in the same camp between the two sides since May, 2008. (dpa)