Britain-based Syrian Observatory for Human Rights says the civlians, including two children, were killed on the outskirts of Maaret al Numan town and in the villages of Kansafra and Khan al Subul.
Clashes ensued when Russian-backed regime forces tried to retake two villages seized by militants and allied rebels earlier this month.
At least 44 regime loyalists, 39 rebel and militant fighters have been killed since Thursday on the edge of rebel-controlled Idlib, Syrian Observatory for Human Rights says.
The civilians, including a dozen people at a busy market, were killed in the rebel and opposition-held Idlib since Tuesday midnight, the Syrian Observatory for Human Rights says.
Britain-based Syrian Observatory for Human Rights reported that 30 people were also wounded in the assaults by Al-Qaeda's former Syria branch, Hayat Tahrir al Sham, and its ally Hurras al Deen.
The deceased include four children while many others were wounded in the explosions in the main city of Idlib.
Presidents of three countries will meet to continue discussions on how to resolve the conflict in Syria as Daesh makes a last stand in the east of the country and Washington prepares to withdraw troops.
Turkey on Thursday deported Johanna Cornelia Boersma for her suspected links to Jabhat al Nusra, a terrorist group with historic links to Al Qaeda, a senior official of the Turkish presidency said.
Days of fighting between the Hayat Tahrir al Sham (HTS) alliance and Turkey-backed National Liberation Front (NLF) ended after the parties reached a ceasefire agreement in Idlib.
Syrian activist and satirist Raed Fares, who was assassinated two weeks ago, ran a radio station called Radio Fresh, which now faces closure amid death threats to staff members and financial crisis as western donors scale back funding.
Raed al Fares gained prominence early in the uprising against Syrian regime leader Bashar al Assad with protest banners that drew international attention on social media.
The Syria summit in Istanbul was a prime opportunity for influencers from the European Union to step up and make their presence felt in finding a solution for Syria. Did they meet the mark?
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