Lebanese President Joseph Aoun sits at the presidential palace in Baabda, east of Beirut, Lebanon. (Photo by AP)

Lebanon`s President Joseph Aoun has condemned Israel for carrying out an environmental crime, following reports that Israeli forces dispersed a mysterious substance over towns in southern Lebanon, which officials in Beirut have described as toxic.

Aoun expressed strong disapproval of the Israeli actions on Wednesday, stating that he instructed government agencies to pursue all necessary diplomatic and legal channels to "address this aggression," which he described as a "clear violation" of Lebanon`s sovereignty.

"This is an environmental and health crime against Lebanese citizens and their land," Aoun was quoted as saying by Lebanon`s official National News Agency.

He said the incident is a "continuation of repeated Israeli attacks on Lebanon and its people".

"These dangerous practices that target agricultural lands and the livelihoods of citizens and threaten their health and environment require the international community and relevant United Nations organizations to assume their responsibilities to stop these attacks," Aoun said.

The UN peacekeeping mission in Lebanon, known as UNIFIL, said on February 2 that the Israeli military had notified them about plans to release a "non-toxic chemical substance" from the air over regions close to the border.

"The [Israeli military] said that peacekeepers should stay away and remain under cover, forcing them to cancel over a dozen activities," UNIFIL said.

Stephane Dujarric, spokesperson for UN Secretary-General Antonio Guterres, said on Tuesday that UNIFIL suspended its operations for nine hours due to the attack, and the force later worked with the Lebanese army to collect samples of the sprayed substance to be tested for toxicity.

UNIFIL condemned the Israeli army`s "deliberate and planned actions" that limited peacekeepers` ability to undertake their mandated activities, and put their health and that of civilians at risk.

"Any activity that may put peacekeepers and civilians at risk is of serious concern," Dujarric had said on Monday. "We reiterate our call on all parties to fully comply with their obligations under [Security Council] Resolution 1701."

Resolution 1701 ended the 33-day-long Israeli military onslaught on Lebanon in the summer of 2006, and demands respect for Lebanon`s sovereignty and territorial integrity. It remains the basis of the ceasefire in south Lebanon.

Israel and Lebanon reached a ceasefire in November 2024 after more than a year of attacks amid the genocidal war in Gaza. More than 4,000 people were killed, and 17,000 others were injured.

Under the ceasefire, Israeli forces were supposed to completely withdraw from southern Lebanon, but have only partially pulled out, maintaining a military presence at five outposts.

In January, Lebanon`s Ministry of Foreign Affairs lodged a complaint with the UN, highlighting 2,036 instances of Israeli violations of the ceasefire during the last quarter of 2025.