Six people, including two children, were killed on Tuesday in Russian strikes on a displacement camp in Syria's northwest, the country's last main rebel bastion, a war monitor said.
Tensions have soared in northwest Syria since a drone attack on a military academy graduation ceremony in Homs earlier this month killed dozens of people, with the regime blaming "terrorists".
"Six civilians, including a woman and two of her children, were killed and eight others injured after Russian warplanes carried out two air strikes on a camp for displaced people" in the west of Idlib province, said the Syrian Observatory for Human Rights.
Hayat Tahrir al-Sham (HTS), led by Al-Qaeda's former Syria branch, controls swathes of Idlib province and parts of the neighbouring Aleppo, Hama and Latakia provinces.
"Russian forces have increased their air strikes since the Homs attack, while HTS intensified its drone strikes," Observatory director Rami Abdel Rahman told AFP.
On Sunday, Syrian army shelling in the country's northwest killed six children, four from the same family, said the British-based group with a wide network of sources inside Syria.
The attack on the military academy in Homs was one of the bloodiest to hit regime forces since the outbreak of the civil war in Syria in 2011.
Civil war erupted in Syria after President Bashar al-Assad's regime crushed peaceful protests.
The conflict has killed more than half a million people and displaced millions after spiralling into a devastating war involving foreign armies, militias and jihadists.