A French soldier was killed and three others wounded while clearing a road in southern Lebanon in an attack that UNIFIL peacekeepers and French officials said on Saturday was likely carried out by Iran-backed Hezbollah.

In calls with Lebanese President Joseph Aoun and Prime Minister Nawaf Salam, French President Emmanuel Macron condemned the "unacceptable attack", his office said in a statement.

Three other members of the United Nations' UNIFIL peacekeeping mission were injured, UNIFIL said, two of them seriously.

UNIFIL said initial assessments indicated the fire came from non-state actors, allegedly Hezbollah, and that an investigation had been launched into what it called "a deliberate attack."

Macron also said the evidence so far pointed to the Iran-backed armed group and urged Lebanese authorities to act against those responsible.

French armed forces minister Catherine Vautrin said the patrol was ambushed while on a mission to open a route to a UNIFIL post that had been isolated by fighting in the area.

The soldier was killed by direct small-arms fire, she said. UNIFIL said the attack occurred in the southern Lebanese village of Ghandouriyeh.

Lebanon's army condemned the shooting and said it had opened an investigation. President Aoun offered condolences and ordered an immediate probe, while Prime Minister Salam also condemned the attack.

UNIFIL was first deployed in 1978 and has remained through successive conflicts, including a 2024 war during which its positions came under repeated fire.

-Enas Alashray in Cairo, Tassilo Hummel in Paris and Olivia Le Poidevin in Geneva. Editing by Emelia Sithole-Matarise and Mark Potter/Reuters