"The Israeli military unlawfully used artillery-fired white phosphorus munitions over homes on March 3, 2026, in the southern Lebanese town of Yohmor," the New York-based rights group said in a report.

HRW added that it "verified and geolocated seven images showing airburst white phosphorus munitions being deployed over a residential part of the town and civil defense workers responding to fires in at least two homes and one car in that area".

In response, the Israeli military said it "is currently unaware and cannot confirm use of shells that contain white phosphorus in Lebanon as claimed."

The army said its policy was not to use shells containing white phosphorus "in densely populated areas, with certain exceptions."

White phosphorus, a substance that ignites on contact with oxygen, can be used to create smokescreens and to illuminate battlefields.

But the munition can also be used as an incendiary weapon and can cause fires, horrific burns, respiratory damage, organ failure and death.

Israel -- which kept up strikes targeting Hezbollah despite a 2024 ceasefire -- launched multiple waves of strikes across Lebanon since last week and sent ground troops into border areas after the Iran-backed group attacked it.

The Israeli army has since repeatedly called on people living south of the Litani River, around 30 kilometres (20 miles) north of the Israeli border, to leave.

At least 394 people have been killed in Israeli attacks, Lebanese authorities said, registering more than half a million people as displaced.

"The Israeli military's unlawful use of white phosphorus over residential areas is extremely alarming and will have dire consequences for civilians," Ramzi Kaiss, Lebanon researcher at HRW, was quoted as saying in the report.

"Israel should immediately halt this practice and states providing Israel with weapons, including white phosphorus munitions, should immediately suspend military assistance and arms sales and push Israel to stop firing such munitions in residential areas," he added.

Lebanese authorities and HRW have over the past years accused Israel of using controversial white phosphorus rounds, in attacks authorities say have harmed civilians and the environment.

Lebanon's state-run National News Agency on Sunday said Israeli forces targeted the towns of Khiam and Tal Nahas, near the border with Israel, "with artillery and phosphorus shelling".

Last month, Lebanon accused Israel of spraying the herbicide glyphosate on the Lebanese side of their shared border, with President Joseph Aoun decrying it as a "crime against the environment".