Foreign ministry spokesman Bernard Valero said the Syrian claim was "a new expression of a flagrant and unacceptable lie" that "shows a degree of impunity against which the international community absolutely must act."
Valero’s comments came after Syrian forces shelled protest hubs and deployed reinforcements in an apparent breach of a UN-backed peace plan, activists and monitors said, as Russia urged its ally to act more decisively to implement the truce.
On the ground, forces loyal to President Bashar al-Assad shelled the villages of Marea and Hawr al-Nahr in northern Aleppo province, said the Syrian Observatory for Human Rights.
Mortar shells also struck old quarters of the flashpoint city of Homs, it said, adding unidentified gunmen killed six soldiers in northeastern Hassakeh province.
But Syrian Foreign Minister Walid Muallem said in Moscow that Damascus had started to carry out the plan tabled by UN-Arab League envoy Kofi Annan by pulling some troops out of certain provinces.
Under the peace plan it agreed with Annan, the Syrian government is supposed to draw back its troops and armour from population centres on Tuesday ahead of a ceasefire on Thursday.
Activists said that instead of withdrawing, the Assad government was sending even more reinforcements into at least one other rebel stronghold, the besieged city of Rastan in central Homs province.
The United Nations says more than 9,000 people have been killed since anti-regime protests broke out in March 2011, while monitors put the number at more than 10,000.