Dozens have died since April 26 in such attacks, war monitor says. Schools, health facilities and residential areas have been hit by the "worst barrel bombing campaign" in opposition-held areas in northwestern Syria in 15 months, UN says.
Russian and Syrian forces intensified air strikes and shelling in northwestern Syria overnight in the heaviest assault on the last opposition and rebel-held area since it was declared a demilitarised zone under a Russian-Turkish deal, sources said on Thursday.
At least eight civilians were killed in the de-escalation zone attacks, White Helmets, officially known as the Syria Civil Defence, said.
"We have information that educational facilities, health facilities and residential areas are being bombed by helicopters and planes," the United Nations regional humanitarian coordinator Panos Moumtzis said from Geneva on Thursday. "The barrel bombing is the worst we have seen for at least 15 months."
Hundreds of artillery shells, and dozens of air raids have brutalized civilian homes and areas of #KafrNabudah City in #Hama since last night. In this continuous Regime bombardment one man was killed and eight others were injured. #Syria pic.twitter.com/slcP1zfbei— The White Helmets (@SyriaCivilDef) April 30, 2019
Idlib and Hama
Air strikes and artillery attacks targeted the villages of Kansafra, Termela, Bsekla Has and Abdin in Idlib province, along with the village of Al Huwaiz and the town of Kafrnabuda in Hama province, sources said.
The targeted villages and towns in northern Hama and southern Idlib fall within a buffer zone agreed on last September between Russia and Turkey as part of a deal that averted a major offensive on the area.
Earlier this week Washington warned violence in the buffer zone "will result in the destabilization of the region."
The air strikes targeting positions in Kafrnabuda and Bsekla were carried out by Russian warplanes stationed at the Khmeimim Air Base in the western Latakia province, opposition sources said.
In a related development, the National Liberation Front, a faction of the Free Syrian Army, reportedly managed to repel an advance on Kafrnabuda by regime ground forces.
Attacks escalate, civilians flee
In September 2018, Turkey and Russia agreed to turn Idlib into a de-escalation zone in which acts of aggression would be strictly prohibited.
Since Tuesday, the Russian and regime forces' attacks have forced thousands of civilians to flee to camps further north along the Turkish border and damaged four medical facilities, according to Idlib Civil Defence officials and a US medical aid organisation working in the area.
"Medical facilities are being evacuated, leaving the most vulnerable with no access to medical care. We are on the edge of a humanitarian catastrophe," Khaula Sawah, vice president of the US-based Union of Medical Care and Relief Organizations -USA (UOSSM US) said in a statement on Wednesday.
Regime helicopters have dropped barrel bombs, which are drums or cylinders packed with explosives and shrapnel that cause indiscriminate destruction.
Attacks between April 26 and 39 killed at least 18 people, according to information shared by rescuers on social media.
1) 14 civilians were killed, and dozens injured, in 24 hours in a new escalation by the "Russian guarantor" and the Syrian regime on the countryside of #Idlib and #Hama, after the failure of the meeting of Astana to reach any agreement in the 12th round pic.twitter.com/ulE859XMHx— The White Helmets (@SyriaCivilDef) April 27, 2019
In response to the escalation, the opposition said they mounted several rocket attacks on Assad's forces' positions including the Breideej army base in northern Hama, injuring and killing at least four Russian soldiers in a mortar attack that hit their vehicle.
"We have stepped up our readiness and sent troop reinforcements to confront any attack [by] the regime and the Russians on any area," Naji al Mustafa, spokesman for the National Liberation Front coalition of opposition groups said.
"We cannot leave matters like this ... we are preparing for any possibility ... " he added.
A military defector told Reuters on condition of anonymity that the latest campaign could signal a ground offensive aimed at taking control of territory in northern rural Hama province and southern Idlib countryside.