The US on Tuesday (April 30th) urged Russia to abide by its commitments and end an "escalation" in Syria's Idlib province, AFP reported.

"The US reiterates that any escalation in violence in north-west Syria will result in the destabilisation of the region," US State Department spokeswoman Morgan Ortagus said.

"We call on all parties, including Russia and the Syrian regime, to abide by their commitments to avoid large-scale military offensives, return to a de-escalation of violence in the area, and allow for unhindered humanitarian access to address the humanitarian disaster created by the ongoing violence," she said.

Russia and Turkey in September agreed to a buffer zone to prevent a potentially devastating regime offensive in Idlib and nearby regions.

But the Syrian Observatory for Human Rights on Friday reported Russian airstrikes in two towns that killed 10 people, including a boy and a girl.

The Observatory said two civilians were killed in Tuesday shelling on Idlib and Hama -- the most intense since the September truce.

"The UN is deeply disturbed by three separate reported attacks on hospitals and health facilities in north-western Syria, depriving thousands of people of their basic right of health," David Swanson of the UN Office for the Co-ordination of Humanitarian Affairs (OCHA) said Tuesday.

The UN did not specify who was behind the attacks, but the Observatory blamed the Syrian regime and Russia.

On Tuesday, a medical centre in Hbeit in southern Idlib was "severely damaged" in artillery shelling, Swanson said, while on Monday, an airstrike hit a hospital in the town of Latamna in neighbouring Hama province, putting it out of service.

A third facility, the Madiq Castle hospital in Hama, was put out of service when it was hit by an airstrike, causing heavy damage to its outpatient clinic, pharmacy and laboratory.