TEHRAN (Press Shia) – The Russian Defense Ministry said it has uncovered an unexploded shell containing mustard gas used by Takfiri militants against civilians in the northwestern Syrian province of Aleppo.

Ammunition containing the chemical agent was reportedly used in a devastating attack on a village in the Aleppo province conducted back in September.

“An express-analysis of the contents (of ammunition) carried out using a portable infrared spectrometer revealed the presence of vesicant chemical warfare agent sulfur mustard. We’ve taken roughly a 20 milliliter sample from the shell. Afterwards it was sealed tight and delivered to the Russian Centre for reconciliation of opposing sides in the Syrian Arab Republic for further investigation,” a representative for Russian Troops of Radiological, Chemical and Biological Defense (RChBD) told journalists, RT reported on Friday.

The recovered chemical round is a crude homemade 240-mm mortar shell, with a capsule in the rear. The capsule contained from 0.5 to 1.5 liters of a black oily liquid, which proved to be a chemical warfare agent.

Over 40 people were injured in the attack they displayed typical symptoms of mustard gas poisoning.

Russian experts previously produced evidence of chemical munitions usage by militants. On Monday, the Russian Defense Ministry said that chlorine and white phosphorus had been found in nine samples from southwestern Aleppo.

Russia is currently working on delivering samples to The Hague for analysis, according to Russia’s FM Sergey Lavrov.

“It will make it hard (for them) to back out,” the minister said, as quoted by TASS.

Mustard gas is a WWI-era chemical warfare agent. The 'anniversary' of its first usage will be next year. Mustard gas has been banned since 1923. However, it has been used in multiple conflicts across the century.