A Syrian opposition official told Al Arabiya's sister channel Al Hadath on Monday that the fragile truce is facing a "complete nullification" because of President Bashar al-Assad government's attacks. Asaad al-Zoubi, head of the Saudi-backed High Negotiations Committee's delegation to peace talks, said the truce which came into effect early on Saturday had collapsed before it started. "We have alternatives to protect our people" if the international community could not, it quoted him as saying without elaborating. Zoubi added there were "no indicators" that the ground was being prepared for peace talks, which the United Nations has said it plans to reconvene on March 7. The Syrian opposition has also sent a letter to the Security Council, saying that Russian war jets on Sunday have executed 26 raids on Syrian rebel factions who were already implementing the ceasefire. The letter also accused Moscow of dropping cluster bombs on residential buildings, which led to the killing of many civilians. France has also called for an immediate meeting of the Syria taskforce to discuss breaches of the cessation of hostilities that came into force on Friday night, French Foreign Minister Jean-Marc Ayrault said on Monday. Ayrault told reporters at the U.N. Human Rights Council in Geneva that he had information about attacks against zones held by moderate rebels in Syria. "We have received indications that attacks, including air strikes are continuing in areas controlled by the moderate opposition," Ayrault told reporters in Geneva. "This must all of course be verified. France has therefore asked that the task force overseeing the implementation of the cessation of hostilities meets without delay," he said on the sidelines of the UN Human Rights Council. Meanwhile, NATO Secretary General Jens Stoltenberg said on Monday the alliance was concerned by a Russian military build-up in Syria. "We are concerned about the significant Russian military build up we have seen in Syria with the ground troops, with the naval forces in eastern Mediterranean and with air forces conducting air strikes," he told a press conference in the Gulf Arab country of Kuwait.