SIDON, Lebanon -Heavy clashes erupted in the Ain el-Helweh Palestinian refugee camp in the southern port city of Sidon Monday after an Islamist militant was killed, a Palestinian official said.

"Issam al-Beqaai was shot when a gunman stormed into his father's clothing store and opened fire," the official told AFP, adding that the victim's body was riddled with bullets.

"Initial reports say he was killed," the official said.

Al-Beqaai was a member of the Islamist group Jund al-Sham.

Armed clashes between Jund al-Sham and its rivals in the Fatah faction erupted after the incident, with fighters opening fire with machine-guns and rocket- propelled grenades.

The Lebanese army immediately took up positions at the camp's entrance, just meters away from the fighting, as dozens of panicked families fled the camp and traffic was cut off. 

Jund al-Sham has in the past clashed with Fatah inside the camp, which is the largest of Lebanon's 12 Palestinian refugee camps and regarded as a hotbed of Islamic extremists.

Jund al Sham, believed to have first appeared in Afghanistan in 1999, was established by Syrians and Palestinians with links to Abu Musab al-Zarqawi, who founded al-Qaeda in Iraq and was subsequently killed by a US airstrike. -Agencies