Kurdish authorities in Iraq say that ISIS used chemical weapons in a January 23 suicide attack against peshmerga fighters, the Associated Press reports.

In a statement, the Kurdistan Region Security Council claimed that ISIS used chlorine gas against peshmerga fighting to seize a supply line along Mosul and the Syrian border. The council said that its fighters found "around 20 gas canisters" on a truck used in the attack. An official told the AP that dozens of Kurdish fighters were being treated for "dizziness, nausea, vomiting and general weakness."

According to Reuters, The council said that the fighters took soil and clothing samples after the attack, and that laboratory analysis showed "the samples contained levels of chlorine that suggested the substance was used in weaponised form."

Peter Sawczak, a spokesman for the Organization for the Prohibition of Chemical Weapons, told Reuters, "We have not had a request from Iraq to investigate claims of use of chemical weapons in Iraq, and the OPCW cannot immediately verify the claims."

The council also released a video taken of the attack, which reportedly shows white smoke pouring out of a truck as it raced towards Kurdish fighters.

Last year, Iraqi officials alleged that ISIS militants used chlorine gas in the towns of Balad and Duluiya in late September. ISIS was also accused of using the chemical weapon in Kobani.

[Photo credit: AP Images]