An Israeli defence official says air force drones are carrying out surveillance missions over its gas fields in the Mediterranean Sea due to security concerns.
Israel and Lebanon do not have an agreed maritime border, and the discovery of the gas fields has created a new source of friction between the two countries, which have clashed repeatedly.
The official wouldn't specify the nature of Israeli concerns today.
Israel has discovered two gas fields thought to contain enough gas to keep it energy self-sufficient for decades.
Lebanon does not claim these fields but energy companies think there might be gas in nearby waters claimed by both countries.