Suspected members of a militant Islamic group fired a rocket-propelled-grenade at a Lebanese army checkpoint near a Palestinian refugee camp .
There was no immediate report of casualties, but the officials, speaking on condition of anonymity because they were not authorized to speak to the media, said the troops returned fire at the suspected Jund al-Sham militants. The attack occurred near the Ein el-Hilweh camp, they said.
The attack comes as Lebanese troops are launching a major attack on another militant Islamic group, Fatah Islam, in the Palestinian refugee camp of Nahr el-Bared near the northern city of Tripoli.
It was not clear if the attack was related to the conflict in the north, but several hardline Islamic groups have called on Muslims to support Fatah Islam.
Late Thursday, a gunbattle erupted in the Ein el-Hilweh camp between the Jund al-Sham group and the mainstream Fatah faction of Palestinian President Mahmoud Abbas.
Jund al-Sham, which is Arabic for Soldiers of Historic Syria, has claimed responsibility or been blamed for a number of bombings and gunbattles, mainly in Lebanon and Syria. Syrian officials have portrayed it as the most active militant group in their country.
Russian officials have repeatedly declared that Israeli aviation poses a threat to the Russian military in Syria.