A collective of Syrian rebel groups on Saturday announced it would consider a ceasefire brokered by Russia and Turkey "null and void" if Syrian government forces continued to violate its terms.
"Continued violations by the regime and the bombardment and attempts to attack areas under the control of the revolutionary factions will make the agreement null and void," the rebels groups said in a statement.
The statement noted that government forces backed by Russian and Iranian forces had advanced into rebel-held areas, particularly areas near Damascus.
According the rebel groups, it appears the opposition and government signed two different versions, one of them missing "a number of key and essential points that are non-negotiable."
While the so-called "Islamic State" (IS) was not included in the ceasefire, the Syrian rebel groups said the former al-Qaeda-affiliate al-Nusra Front, rebranded as Jabhat Fateh al-Sham, had been considered as one of the opposition groups among the deal.
The rebels' statement contradicts the Syrian military, which on Thursday said the former al-Qaeda affiliate had not been named among the opposition groups.
The UK-based Syrian Observatory for Human Rights (SOHR), an independent monitor that utilizes a nationwide network of on-the-ground informants, said on Saturday that the ceasefire has largely held across the country, although clashes and airstrikes have persisted in some parts.
In the wake of the government's victory in Aleppo, Russian President Vladimir Putin on Friday said he would reduce Moscow's military contingent in Syria. Russia entered the conflict in September 2015 in a bid to bolster the regime of Syrian President Bashar al-Assad, a key regional ally.
Meanwhile, Russian ambassador to the UN Vitaly Churkin said the UN Security Council would vote on a resolution aimed at sanctioning the ceasefire in Syria and peace talks scheduled for January in Kazakhstan.
Steffan de Mistura, the UN's Syria envoy, said the talks should aim to complement the UN-brokered peace talks, which have failed to mediate a political solution to the nearly 6-year-old conflict.
Churkin said the draft resolution had been amended after UN member states on the Security Council reviewed it on Friday, adding that he expects them to "adopt it unanimously."
More than 300,000 people have been killed and half the population displaced since the conflict erupted in 2011, when government forces launched a bloody crackdown on peaceful protesters calling for Assad to step down.
ls/rc (Reuters, AFP, AP)