Britain, Germany and France called on Monday for an end to the military escalation in north western Syria, saying they were gravely concerned at recent violence which had led to the death of more than 120 civilians.
Last week, Syria's army, backed by Russian air power, launched ground operations against the southern flank of a rebel zone consisting of Idlib and parts of adjacent provinces.
"This military escalation must stop," the joint statement from the three countries, issued by Britain's Foreign Office, said.
"Airstrikes on population centers, indiscriminate bombardment and use of barrel bombs as well as the targeting of civilian and humanitarian infrastructures, notably schools and health facilities, are blatant violations of International Humanitarian Law."