"It became known that terrorist groups are preparing provocative attacks by chemical weapons on Syrian army's positions and residential areas in the east part of Aleppo to accuse government forces [of the attacks]," Lt. Gen. Viktor Poznikhir, the first deputy chief of the Main Operational Directorate of the Russian General Staff, said.
The cessation of hostilities in Syria was undermined by militant groups that have increased their activities, he added.
"We were ready to prolong the ceasefire regime consistently, striving to extend it indefinitely. At the same time the cessation of hostilities was derailed by militants. Not only did the intensity of shelling of government forces positions [by militants] fail to subside, but the armed groups' activity increased," Poznikhir said.
The Russian Defense Ministry said that the situation in Syria has deteriorated as militants have regrouped and launched offensives in Aleppo and Hama provinces.
"As a result of the situation in the Syrian Arab Republic has escalated significantly. In the provinces of Aleppo and Hama, opposition groups, taking advantage of the seven-day truce, replenished the stocks of ammunition and weapons, to regroup and started offensive operations in order to capture new territories."
On Tuesday, Syrian government forces liberated most of the al-Farafira district northwest of Aleppo's historic Old City and advanced the frontline for the first time in years.