The death toll, which includes children, is likely to increase as some of those wounded are in a serious condition, while others are still missing or trapped under rubble, the watchdog said.
Since late April, the forces of Syrian President Bashar al-Assad, supported by Russian air power, have been waging a massive campaign against rebels in the provinces of Hama and Idlib, the last major opposition strongholds in the country.
The offensive has so far killed 680 civilians, among them 176 children, and displaced more than 300,000 people, according to the observatory.
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