Rebel fighters from the Jaish al-Fatah (or Army of Conquest) brigades watch as smoke billows in the background on November 3, 2016, at an entrance to Aleppo, in the southwestern frontline near the neighbourhood of Dahiyet al-Assad, during a rebel offensive to break a three-month siege of the opposition-held east of Syria's second city. (AFP/Xinhua)

MOSCOW, Nov. 11 (Xinhua) -- Russia's Defense Ministry said Friday that it has discovered proof of terrorists using chemical weapons against civilians and the Syrian military in the southwestern outskirts of the Syrian city Aleppo.

"Experts of the Russian Defense Ministry have found unexploded artillery ammunition of the terrorists containing toxic substances," the ministry's spokesman Maj. Gen. Igor Konashenkov said in a statement.

An express test of the munitions, shell fragments and soil samples in a mobile laboratory revealed with a very high probability that the substances used were chlorine and white phosphorus, the statement said.

A profound analysis of the toxic substances found in Aleppo will be conducted in the laboratory of the Scientific Center of the Russian Nuclear, Biological and Chemical Protection Troops, licensed by the Organization for the Prohibition of Chemical Weapons (OPCW), it added.

The situation in the contested city of Aleppo has gone downhill since several rounds of truce efforts have barely held as militants in eastern Aleppo reportedly violated the ceasefire, killing civilians.