UNITED NATIONS/BEIRUT - UN Secretary-General Antonio Guterres on Saturday strongly condemned the attack that killed one French peacekeeper serving with the United Nations Interim Force in Lebanon (UNIFIL) and injured three others earlier in the day, his spokesperson said in a statement.

"Attacks on peacekeepers must stop. They are grave violations of international humanitarian law and of Security Council Resolution 1701 (2006) and may amount to war crimes," said the statement, issued by spokesperson Stephane Dujarric.

Guterres reiterated his call on all actors to uphold their obligations under international law, ensure the safety of UN personnel and the inviolability of UN property and assets, and respect UNIFIL's freedom of movement, the statement said.

"All attacks on peacekeepers must be promptly investigated, and those responsible must be effectively prosecuted and held accountable," it said.

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The statement noted that according to a UNIFIL initial assessment, the peacekeepers came under fire from non-state actors, presumed to be Hezbollah, while investigating a location where suspected improvised explosive devices had reportedly been placed on a road between two United Nations positions in the UNIFIL area of operations in southern Lebanon.

This is the third incident in recent weeks to have resulted in the deaths of peacekeepers serving with UNIFIL and occurred despite a 10-day cessation of hostilities announced on April 16, the statement said, urging all actors to respect the truce and cease fire.

"The Secretary-General expresses his deepest condolences to the family, friends, and colleagues of the peacekeeper who died, and to the Government and people of the French Republic. He wishes a full and fast recovery to the injured peacekeepers," the statement said.

Hezbollah denies involvement

In a statement, Hezbollah denied any involvement and called for "caution in assigning blame and responsibility" until the Lebanese Army's investigation clarifies the incident.

The group also stressed the importance of continued cooperation between local residents, UNIFIL, and the Lebanese Army.

French President Emmanuel Macron said on the X platform that "everything suggests" the attack was the responsibility of Hezbollah and called on Lebanese authorities to immediately arrest those responsible.

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Meanwhile, Hezbollah's leader Naim Qassem said on Saturday the ceasefire with Israel must mean a complete halt to aggression, warning the group will retaliate against Israeli violations in southern Lebanon.

"There is no ceasefire from one side only," Qassem said in a statement, adding that Hezbollah fighters "will respond to violations of aggression accordingly."

He outlined five key steps: a permanent halt to hostilities across Lebanon, a full Israeli withdrawal, detainee releases, the return of displaced residents, and reconstruction with Arab and international support.

Hezbollah had not been defeated and would continue to pursue Lebanon's liberation and independence, he added.

Qassem also said Hezbollah is open to "a new page" of cooperation with the Lebanese government, stressing readiness to work with state institutions to strengthen national unity and safeguard sovereignty.

READ MORE: 10-day Israel-Lebanon ceasefire takes effect

A 10-day ceasefire between Israel and Lebanon took effect at midnight between Thursday and Friday local time (2100 GMT), following an earlier announcement by US President Donald Trump.

However, the Israel Defense Forces said in a statement on Saturday that it had struck militants approaching a "Yellow Line," which marks the northern edge of the "security zone" established by Israel in southern Lebanon, over the past day.

The Israeli army also began constructing a new military site on Saturday near Kfarchouba village in the eastern sector of southern Lebanon's border area, according to eyewitnesses and a Lebanese security source.

The Lebanese security source told Xinhua that an Israeli military unit, comprising bulldozers and excavators, and protected by a Merkava tank, was conducting earthmoving works on a hill southwest of Kfarchouba. Activities included ground leveling, excavations, and the construction of earth berms, indicating the establishment of a new military post administratively linked to Kfarchouba.

Eyewitnesses identified the site as "Rbaa al-Teben" hill, about 1.5 km from the Lebanon-Israel demarcation line and home to olive groves and vineyards.