BEIRUT (Reuters) - An Israeli airstrike killed two civilians travelling in a car along Lebanon's southern coast on Monday, security sources said, including an employee of a cleaning company that is contracted by the United Nations peacekeeping force in Lebanon.

The force, known as UNIFIL, confirmed that a vehicle driven by the cleaning worker was hit by a strike near the southern Lebanon town of Naqoura, killing both the driver and passenger.

"UNIFIL deplores that so many people have been hurt or killed since 8 October. Attacks on civilians are violations of international humanitarian law. They must stop," said UNIFIL spokesperson Kandice Ardiel.

There was no immediate comment from the Israeli military.

The security sources said the strike was Israeli and that the two men travelling in the car were cousins. Lebanese armed group Hezbollah later said it had fired Katyusha rockets into Israeli territory in retaliation for the strike near Naqoura.

Nearly 140 civilians have been killed by Israeli bombardment of Lebanon since Oct. 8, when hostilities broke out between the Israeli military and Hezbollah in parallel with the war in Gaza.

In May, an Israeli strike on a village in southern Lebanon killed a technician contracted by a telecoms company to fix a phone tower.