Al-Qaida's Syrian affiliate has attacked positions manned by Lebanon's Shiite Hezbollah along the Syrian border, killing eight of its fighters.

An official close to Hezbollah declined Monday to say how many fighters were killed in Sunday's battles with the Nusra Front, but in mosques across Lebanon's eastern Bekaa valley funerals were announced for eight Hezbollah fighters.

The fighting on Sunday lasted for several hours. The official said Hezbollah's response to the attack was "huge, strong and fast." The official spoke on condition of anonymity because he is not authorized to speak to reporters.

Hezbollah began sending fighters to reinforce Syrian President Bashar Assad's troops last year, saying it needed to protect Lebanon from the threat of Sunni extremism.