A French soldier has been shot dead after UN peacekeepers were ambushed by an armed group in southern Lebanon.   

He suffered a 'direct gunshot' wound after the patrol came under 'small-arms fire' on Saturday morning, with three others injured in the attack. 

Attempts were made to resuscitate him but he 'tragically succumbed to his injuries'. 

French president Emmanuel Macron has blamed Hezbollah for the incident, which occurred just one day after the ceasefire between Lebanon and Israel took effect on Friday, and he urged the Lebanese authorities to arrest the perpetrators. 

'Everything suggests that responsibility for this attack lies with Hezbollah,' he wrote in a social media post. 

'France demands that the Lebanese authorities immediately arrest those responsible and assume their responsibilities alongside UNIFIL,' he said regarding the UN mission in southern Lebanon.

Catherine Vautrin, the French armed forces minister, said the UN peacekeepers had been on a mission to open a route towards a UNIFIL post when the ambush occurred. 

The post had been isolated for several days due to fighting in the area between Hezbollah and Israeli forces.

Vautrin said on social media the deceased French soldier had been 'caught in an ambush by an armed group at very close range'. 

'Immediately hit by a direct shot from a light weapon, he was pulled back under fire by his comrades, who were unable to resuscitate him,' she said.  

UNIFIL said the peacekeepers 'came under small-arms fire from non-state-actors' in a 'deliberate attack' as they were 'clearing explosive ordnance along a road in the village of Ghanduriyah' to get to the outpost.  

'Tragically, one peacekeeper succumbed to his injuries and three others were injured, two of them seriously,' it added. 

UNIFIL has carried out its own assessment of the attack, reporting that incoming fire had been directed on its troops by 'allegedly Hezbollah'. 

It said it had also launched an investigation into what 'may amount to war crimes'.

Macron spoke with Lebanese president Joseph Aoun and prime minister Nawaf Salam following the attack 'to call on the Lebanese authorities to shed full light on this incident' and 'identify and prosecute those responsible without delay', his office said. 

The French president also urged Lebanon to 'do everything possible to ensure the safety of UNIFIL soldiers, who must under no circumstances be targeted'. 

Salam said he has ordered an investigation into the fatal ambush and to bring the perpetrators to justice. 

Lebanese politicians and the army have condemned the attack in a statement, with the army saying it will continue its 'close coordination' with UNIFIL.  

UNIFIL patrols southern Lebanon, near the Israeli border where Israel and Hezbollah have been fighting since last month, after the Iran-backed militant group drew Lebanon into the Middle East war with rocket fire at Israel in support of Iran.

Three Indonesian peacekeepers were killed last month, with a preliminary UN investigation finding one was killed by Israeli tank fire, while the two others were killed by an improvised explosive device likely planted by Hezbollah.

Other UNIFIL peacekeepers have also been wounded since the war erupted, and in April, Israeli soldiers destroyed surveillance cameras in UNIFIL's headquarters, the peacekeeping body said.

Last week, an Israeli tank twice rammed peacekeeping vehicles, causing damage but no injuries, according to UNIFIL.

UN peacekeepers have served as a buffer between Lebanon and Israel for decades, but their mandate concludes at the end of this year. 

Hezbollah has denied it was involved in the deadly attack after Macron accused the group of orchestrating the ambush. 

In a statement the group said: 'Hezbollah denies any connection to the incident that occurred with UNIFIL forces in the Ghandouriyeh-Bint Jbeil area, and calls for caution in making judgments and assigning responsibilities regarding the incident pending the Lebanese army's investigations to determine the full circumstances of the incident.'