SIDON, Lebanon (AFP) - Palestinian security forces on Saturday (Aug 19) battled radical Islamist gunmen in Lebanon's largest Palestinian refugee camp near the southern port of Sidon, for the third consecutive day.

The clashes first broke out on Thursday when gunmen from the small Islamist Badr group opened fire on a position of Palestinian security forces inside Ain al-Hilweh camp, a Palestinian source said.

Two people were killed in that fighting.

An AFP reporter said the clashes eased on Friday before intensifying again on Saturday, forcing dozens of families to flee the camp and seek shelter in Sidon mosques.

The sound of fierce gunfire and rocket fire could be heard outside the camp as black smoke billowed over Ain al-Hilweh, said the reporter.

The fighting shook the Al-Tiri district a few metres (yards) away from a Lebanese army position.

By longstanding convention, the Lebanese army does not enter Palestinian refugee camps in Lebanon, leaving the factions themselves to handle security.

The Islamist group is linked to Bilal Badr, a militant wanted in connection with "terrorism" who has refused to surrender, according to a Lebanese security official.

In April, his supporters also clashed intermittently for a week with Palestinian security forces, in violence that left nine dead and more than 50 wounded.

A joint Palestinian security force, comprising members of the key Fatah and Hamas factions, has for months strived to rein in Badr fighters.

Ain al-Hilweh - the most densely populated Palestinian camp in Lebanon - is home to some 61,000 Palestinians, including 6,000 who have fled the war in neighbouring Syria.

Several armed factions including extremist groups have a foothold in the camp which has been plagued for years by intermittent clashes.