Iraqi Kurdish authorities said Saturday that their troops are being attacked by Islamic State fighters using chemical weapons.

The Kurdish Regional Security Council released a statement saying it has evidence showing the ISIS fighters used chlorine gas as a chemical weapon against Kurdish military forces known as peshmerga fighters.

The council said the alleged chemical attack took place on a road between Iraq's second-largest city, Mosul, and the Syrian border, as forces fought to seize a vital supply line used by the Sunni militants. It said its fighters later found "around 20 gas canisters" that had been loaded onto the truck involved in the attack.

Video provided by the council showed a truck racing down a road, white smoke pouring out of it as it came under heavy fire from peshmerga fighters. It later showed a white, billowing cloud after the truck exploded and the remnants of it scattered across a road.

An official with the Kurdish council told The Associated Press that dozens of peshmerga fighters were treated for "dizziness, nausea, vomiting and general weakness" after the attack. He spoke on condition of anonymity as he was not authorized to discuss the incident.

The assertion has yet to be verified, but such battlefield tactics are banned under the 1997 Chemical Weapons Convention.

"The fact ISIS relies on such tactics demonstrates it has lost the initiative and is resorting to desperate measures," the Kurdish government said in the statement,

The security council said in the statement that the evidence is from a January 23 car bombing in northern Iraq and includes independent lab results from soil and clothing in connection with the incident.

The United States is leading a coalition of forces to try to stop the Islamic State, whose sudden and deadly rise in parts of Iraq and Syria has shocked much of the world.

President Obama began air strikes against the group in both countries starting in August 2014. The U.S. alone has flown roughly 900 combat missions over Iraq since that time. Roughly 2,000 U.S. troops are also in Iraq to help train anti-Islamic State forces, but no American combat soldiers are being sent to the region.  

Chlorine, an industrial chemical, was first introduced as a chemical weapon at Ypres in World War I with disastrous effects as gas masks were not widely available at the time. While chlorine has many industrial and public uses, as a weapon it chokes victims to death.

There have been several allegations that the Islamic State group has used chlorine as well. In October, Iraqi officials claimed Islamic State militants may have used chlorine-filled cylinders during clashes in late September in the towns of Balad and Duluiya. Their disclosures came as reports from the Syrian border town of Kobani indicated that the extremist group added chlorine to an arsenal that already includes heavy weapons and tanks looted from captured military bases.

Insurgents have used chlorine gas in Iraq before. In May 2007, suicide bombers driving chlorine tankers struck three cities in Anbar province, killing two police officers and forcing about 350 Iraqi civilians and six U.S. troops to seek treatment for gas exposure. Those bombers belonged to Al Qaeda in Iraq, which later became the Islamic State group.

The Associated Press contributed to this report.