BEIRUT (Reuters) - Islamic State may have fired seven Grad rockets into Lebanon on Monday from its enclave on the border with Syria, without causing any injuries, a Lebanese security source said.

It would mark the first use of those weapons by Islamic State fighters there for several years, and comes as the Lebanese army prepares for an expected assault on their enclave.

The rockets fell around the town of al-Qaa and led the Lebanese army to shell Islamic State positions in the hills nearby, the source said.

Fighters from Islamic State and the former Nusra Front group established pockets in the rugged border area near the Lebanese town of Arsal early in the six-year Syrian civil war, the biggest spillover of the violence so far into Lebanon.

Lebanon’s Shi’ite Hezbollah group late last month forced the Nusra fighters to quit their pocket after a brief offensive, and the Lebanese army is expected to launch an assault on the Islamic State enclave soon.

The Islamist militants and the Lebanese army have exchanged frequent shell, mortar and small arms fire over several years.