A Lebanese security official says Hezbollah fighters and Syrian rebels have exchanged fire in a remote area of eastern Lebanon overnight, leading to a number of deaths on both sides.

Hezbollah and Syria's rebels fight on opposite sides in Syria, but have rarely clashed on Lebanese territory.

The official said Sunday that members of Hezbollah appear to have ambushed and encircled a group of Syrian rebels along with some Lebanese fighters whom they suspected of rocketing Lebanon's Baalbek region a day earlier.

He says there were unconfirmed reports that a Hezbollah fighter and a number of Syrian rebels were killed.

He spoke on condition of anonymity in line with military regulations and because the details were not yet clear.

The clashes took place in a remote area near Syria.