Attacks were intensified on villages and towns in northern Hama, southern Idlib and Latakia — areas that fall within a demilitarised zone agreed on last September between Russia and Turkey.
The Syrian opposition said on Saturday the regime's army and their allies were intensifying attacks on a demilitarised zone in the northwest in an attempt to undermine a Russian-Turkish deal that has averted a major offensive on their last stronghold.
They said the regime stepped up its onslaught with hundreds of mortar and rocket attacks on a string of rebel and opposition villages and towns in northern Hama, southern Idlib and Latakia that fall within a demilitarised zone agreed on last September between Russia and Turkey.
"The regime has targeted all the fronts in the demilitarised zone. We have responded by striking at their military posts that have struck populated villages and towns," said Captain Naji Abu Huthaifa, a spokesman for the National Liberation Front, an alliance of Turkish-backed fighters.
Russia and Turkey reached a deal in Sochi last September to enforce a demilitarised zone in Idlib and adjacent areas that are the last stronghold of the opposition which rose up against the regime leader Bashar al Assad in 2011.
Idlib province is also home to an estimated 3 million people, more than half of whom have already been displaced at least once during the war.
The regime army and allied militants had wanted to press on to regain the last of such areas after recapturing southern Syria and ending insurgent control around the capital.
Syrian regime media, quoting army sources, blamed opposition and rebels for the attacks and accused them of trying to wreck the Russian-Turkish initiative.
The main militant group, Tahrir al Sham, has so far not withdrawn heavy weapons, a regional intelligence source said on Saturday.
A suicide attack by Ansar al Islam militant group on a regime army checkpoint on Friday had killed at least 23 soldiers, rebels said.
The attacks have also forced hundreds of families that had earlier been encouraged to return to some of the frontline villages in the zone to flee further north near the Turkish border, residents said.
Daesh loses holdout in south
Syrian regime forces retook control of the last southern holdout of Daesh on Saturday, as a monitor said air strikes killed dozens in a remaining rebel pocket in the country's east.
More than seven years into Syria's grinding civil war, multiple forces are battling to push Daesh out of its remaining scraps of territory in the country.
On Saturday, regime forces retook the southern area of Tulul al Safa as Daesh pulled back into the desert after months of fighting, the Britain-based Syrian Observatory for Human Rights said.
The regime forces regained control of the volcanic plateau between the provinces of Damascus and Sweida "after IS [Daesh] fighters withdrew from it and headed east into the Badia desert," Observatory chief Rami Abdel Rahman said.
The withdrawal likely came "under a deal with the regime forces" after weeks of encirclement and air raids, he said.
In recent weeks, air strikes on the Tulul al Safa pocket had increased and hundreds of regime forces were sent as reinforcements, the Observatory said.
State news agency SANA reported regime forces had made "a great advance in Tulul al Safa" and said they were combing the area for any remaining militants.
That victory has whittled down the group's territorial control to a single pocket in the east of the country, where it faces a separate assault by US-backed forces.