Warplanes bombed a rebel-held area east of Damascus on Wednesday where Russia declared a ceasefire less than 24 hours earlier, the Syrian Observatory for Human Rights reported.
There was no immediate comment from the Syrian military.
Russia's Defense Ministry said on Tuesday a ceasefire had been agreed in Eastern Ghouta in Syria's Damascus province until March 20. The Observatory said air strikes and artillery had hit three towns there.
A media unit run by Damascus ally Hezbollah said the Syrian air force had hit jihadists tied to Syria's former al Qaeda offshoot in Irbeen city north east of Damascus, and also in al Qaboun, both in Eastern Ghouta.
The Syrian army has been closing in on the area in recent months, and towns there have seen an escalation of aerial raids and fighting on several frontline in recent days, according to opposition sources.
The army and its allies are seeking to force rebels to agree to truce deals similar to those that have led to evacuating thousands of opposition fighters to areas in the country's north.
Before the Syrian conflict began in 2011, over half a million people lived in Eastern Ghouta, once a major economic hub serving the capital but now an ever shrinking area of sprawling urban districts and farmland whose population has dropped to tens of thousands.
REUTERS
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