"A new Amnesty investigation has found that the Israeli army indiscriminately, and therefore unlawfully, used white phosphorus in an attack on Dhayra in south Lebanon on 16 October," wrote Amnesty International on X, formerly known as twitter.
The attack injured at least nine civilians and damaged civilian objects.
"The attack must be investigated as a war crime." it noted.
The investigation also documented two other instances of white phosphorus use in populated areas in south Lebanon on 10 and 15 October, respectively.
"It is beyond horrific that the Israeli army has indiscriminately used white phosphorus in violation of international humanitarian law" said Aya Majzoub, Deputy Regional Director for the Middle East and North Africa at Amnesty International.
Multiple international NGOs have accused the Israeli military of using the incendiary weapon against Gaza during the current round of fighting.
The use was first reported by the Palestinian News Agency WAFA in a Facebook post on 11 October, where a video was posted showing the supposed use of the weapon.