The Russian General Staff said Monday that US-backed Syrian rebels have not separated from terrorists, but united with al-Nusra Front and are preparing for an offensive.

The only parties adhering to the truce are Moscow and the Syrian government forces, while the United States and opposition groups it controls have not fulfilled a single obligation according to the Russia-US agreement, the General Staff said.

"The United States and so-called moderate opposition groups under its control have not fulfilled a single commitment taken on under the Geneva agreements. Above all, the moderate opposition has not been separated from al-Nusra Front [also known as Jabhat Fatah al Sham]," Lt. Gen. Sergei Rudskoy said at a briefing.

Syrian rebels have taken advantage of the ceasefire observed by the Syrian army and currently are preparing to advance in the Aleppo and Hama provinces, the Russian reconciliation center said.

"In the provinces of Aleppo and Hama, opposition units used the ceasefire to regroup, get more ammunition and prepare for an offensive to capture more territories, while the Syrian troops have ceased combat operations," Lt. Gen. Vladimir Savchenko said.

"The joint US-Russian statement on the cessation of hostilities in Syria reached on February 22, 2016 says that our states 'will also work together…to delineate the territory held by Daesh, al-Nusra Front and other terrorist organizations designated by the UN Security Council.' Unfortunately, our US colleagues still have not made any real steps in this direction," the Russian Defense Ministry said.

Syrian opposition forces violated the truce more than 300 times since the ceasefire came into force, killing 153 Syrian personnel and 63 civilians, the Russian General Staff said.

"In the past 24 hours alone, the number of shelling attacks by militant groups reached 53 episodes. The cessation of hostilities regime has been violated a total of 302 times since it came into effect. During this period, 63 civilians died and 252 were injured, Syrian armed forces lost 153 service members," Lt. Gen. Sergei Rudskoy, the head of the Russian Chief of the General Staff's Main Operational Directorate, said.

The Russian reconciliation center said that militants' shelling of residential districts of Aleppo killed 10 civilians, including 2 children, and wounded 30 others.

"They attack not only positions of the government’s forces but also residential neighborhoods with civilian population. Within last 24 hours, ten civilians, including two children, were killed in the shelling from the militants-held areas. Thirty people were injured."

The Russian General Staff said it suspects the US of attempts to create such a situation in Syria to accuse Moscow and Damascus of disrupting the delivery of humanitarian aid.

The issue of providing humanitarian access to besieged areas of Aleppo has also not been resolved, Rudskoy added, stressing that opposition fighters have failed to adhere to the agreement and to set up a checkpoint to allow aid convoys to pass through safely.

"Armed groups under US control have not set up a checkpoint in the eastern part of the Castello road [north of Aleppo] and have not handed it over to the Syrian Arab Red Crescent. Fighters, weapons and equipment have not been withdrawn from Castello."

The Syrian Army pulled out heavy military equipment from the front lines along the Castello road on Thursday night to create a demilitarized zone that is vital for safe delivery of humanitarian air to residents of Aleppo.

The Russian General Staff said that neither Russian, not Syrian aviation carried out airstrikes in the past week.

On September 9, Russian Foreign Minister Sergey Lavrov and US Secretary of State John Kerry announced a new peace plan to address the conflict in Syria that called for a ceasefire and anti-terrorism cooperation among other clauses of the treaty.