Nearly 100 combatants were killed on Friday in clashes between fighters loyal to Syria's government, rebels and jihadists in northwestern Syria, a war monitor said.
Starting at dawn on Friday morning -- and after bombing by the regime -- fighting in northern Hama province killed 51 government loyalists and allied militiamen, and 45 among the rebels and jihadists, said the Syrian Observatory for Human Rights.
The clashes continued in the afternoon, the Britain-based Observatory said.
Backed by its ally Moscow, Damascus has since late April intensified bombardment of much of Idlib province and the parts of neighbouring Hama, Aleppo and Latakia where Syria's former Al-Qaeda affiliate Hayat Tahrir al-Sham (HTS) holds sway.
Fighting has meanwhile taken place on the ground in parts of these anti-regime areas, particularly in northern Hama.
Syria's official SANA news agency also reported bombardment on Friday.
"Units of the army today carried out massive bombing at dawn.... on positions of the terrorist Al-Nusra Front in (and) around the villages of Jibine and Tal Maleh," SANA said, referring to positions held by HTS.
The bombardment led to "the destruction of the terrorists' fortifications and their lines of defence", it added.
They took place in response to attacks against the villages and cities in Hama, the news agency said.
Idlib and parts of neighbouring Hama, Aleppo and Latakia provinces were supposed to be protected by a buffer zone under an September agreement between Russia and Turkey.
But the region has come under increased bombardment by the regime and its Russian ally since HTS seized most of Idlib at the start of the year.
The Turkish defence ministry said Friday a Turkish soldier was killed and three others were wounded the day before by fire from Syrian government forces against a Turkish observation post in Idlib province.
Since late April, air strikes have killed 490 civilians, according to the Observatory, while fighting has killed 682 pro-regime forces and 821 rebels and jihadists.
The flare-up has also displaced 330,000 others, according to the United Nations, sparking fears of one of the worst humanitarian disasters in Syria's eight-year war.
The conflict in Syria has killed more than 370,000 people and displaced millions since it erupted in 2011 with the brutal repression of protests against President Bashar al-Assad.