At least 13 civil were killed in airstrikes by the Syrian army on a popular market in Maarat al-Nauman, the Syrian Observatory for Human Rights reported.
Maarat al-Nauman has been targeted on several occasions since mid-November by the Syrian military with a motive to gain territory in the southern portion of Idlib, Efe news reported.
A Russian attack on Idlib's central prison left three dead a woman and her two children who were visiting the facility, according to the UK-based NGO, which has a wide network of collaborators on the ground.
The penitentiary is run by the Organisation for the Liberation of the Levant, an Islamist alliance that includes the former Syrian Al-Qaeda affiliate and which has been attacked repeatedly over the past few months.
In the Russian attack, 17 people were injured, while an unknown number of inmates managed to escape.
One civilian was killed in an attack on the city of Saraqib, the source added.
Another civilian was killed in Kanayes and a woman was killed near Maarat al-Nauman.
Meanwhile, the Syrian Civil Defence, known as the White Helmets, confirmed that the Syrian army and Russian warplanes attacked two markets one in Saraqib and the other Maarat al Nauman.
Neither Moscow nor Damascus reacted to the reports.
The pro-government forces have managed to regain control over some areas of the province thanks to an offensive launched in April.
The operation was suspended in August, however, when a ceasefire was implemented.
Since the army resumed the military operation mid-November, it has seized several areas, while launching nearly daily bombardments with the support of Moscow.
The Organisation for the Liberation of the Levant, which controls most of Idlib, is considered to be a "terrorist" organization and is the main target of both the Syrian and Russian governments.
( With inputs from IANS )