Air strikes killed at least 11 people in rebel-held northwestern Syria on Sunday, the Syrian Observatory for Human Rights reported, and the Syrian state news agency said the army had repelled an attack by militants in the area.
In central Syria, state media also said that a train carrying phopshate was derailed by a bomb blast east of Palmyra, causing injuries among the crew.
It did not identify the perpetrators of the attack. Islamic State group militants are still active in central Syria.
The northwest is the last major foothold of the rebellion against President Bashar al-Assad, who has vowed to recover the whole country but has made little or no gains in more than two months of military operations in the area.
The Observatory said Syrian government air strikes killed six people, including a child, in the village of Urum al-Jawz in western Idlib province.
Four more people, including two children, were killed in strikes on Kfarouma in the south of the province.
A Russian air strike killed a civil defence volunteer in the town of Khan Sheikhoun, the Observatory said.
The civil defence, also known as the White Helmets, identified him as Anas al-Diab, a volunteer and media activist it said was killed while documenting the air strikes.
The Observatory said the deaths increased the number of civilians killed by Syrian government or Russian bombardments in the northwest to 682 since late April. It said 53 civilians had been killed by rebel attacks on state-held areas in the same period.
Some 1,500 combatants on both sides have been killed in the same period, it said.
Syrian state news agency SANA said the Syrian army had repelled an attack by militant groups who had targeted army positions protecting the village of al-Qasabiya in southern Idlib.
SANA said army units destroyed vehicles belonging to the Nusra Front and its affiliates had been destroyed in the attack, during which the militants used suicide bombers.
The Nusra Front is today known as Tahrir al-Sham, a jihadist organisation that holds sway in the Idlib area.