The army patrol giving chase "was ambushed and came under fire," a statement said.

It said one gunman was killed and the driver of the vehicle was arrested, without providing additional details.

Lebanon's prime minister Hassan Diab condemned the ambush, saying an attack on the army is an attack on all Lebanese.

"What is required at this moment is to speed up the arrest of the attackers," he said, without identifying those responsible, in a statement carried by state-run National News agency.