Syria may have used chemical weapons against rebels in the city of Saraqib in an attack in February 2018. according to a report published Tuesday.

he report published by the Organization for the Prohibition of Chemical Weapons alleged that Syria's elite "Tiger Forces" dropped chlorine on top of the rebel-held city.

The OPCW report said a helicopter controlled by the military unit dropped a cylinder that released toxic chlorine gas, which dispersed over a large area. The organization said at least a dozen individuals were exposed to the chemicals and suffered symptoms such as nausea, chest pain, and skin irritation.

"There are reasonable grounds to believe that, at approximately 21:22 on 4 February 2018, during ongoing attacks against Saraqib, a military helicopter of the Syrian Arab Air Force under the control of the Tiger Forces hit eastern Saraqib by dropping at least one cylinder," the OPCW said.

The OPCW said it had credible witnesses that saw the helicopter drop the cylinder of chlorine. One of the witnesses said he went to see what was dropped and then immediately "started feeling sick." The OPCW said it also had video evidence of the chemical attack.

Despite presenting its evidence, the Assad regime continued to deny that it had used chemical weapons. The latest report is the second time the OPCW had accused Syria of using chemical weapons during its civil war.

In 2017, the Assad regime was accused of using a Sarin nerve agent and chlorine against civilians in the town of Ltamenah. At least three people were reportedly killed by the chemical weapons attack, while 32 others had suffered serious injuries due to exposure.

The OPCW said its report relied heavily on interviews with witnesses and victims of the latest attack. It also talked with medical personnel who attended to the victims. The organization also obtained toxicology samples from the victims.

In response to the latest report, Syrian authorities accused the organization of "staging" the incident and working with jihadi groups to "forge accusations against the Syrian Arab Army."