At least 20 civilians were killed on Sunday as Syrian regime forces were poised to retake a key motorway connecting Damascus to second city Aleppo, after weeks of battles in the rebel-held Idlib region, a monitor said.

The regime and its Russian ally have been engaged in a fierce weeks-long offensive to take back the vital M5 artery which connects Aleppo, once Syria’s economic hub, to Damascus and the Jordanian border.

A section of the highway southwest of Aleppo city still lies under control of rebels and jihadists who dominate a shrinking, densely populated territory centred on neighbouring Idlib province.

Pro-regime forces have been chipping away at the area in an assault that has sent half a million people fleeing north towards the Turkish border.

Deadly raids on Sunday by regime ally Russia left 14 people dead, including nine in the village of Kar Nuran in southwestern Aleppo province, near the last stretch of the M5 still in rebel hands, said the Syrian Observatory for Human Rights.

Syrian air raids with crude barrel bombs also killed four civilians in the Atareb district east of Aleppo, while another died in artillery fire near the city of Jisr Al-Shughur, it said.

The last civilian was killed in regime air strikes on Ketian village in southern Idlib.

Recapturing the M5 would allow traffic to resume between war-torn Syria’s main business hubs, helping the regime revive a moribund economy after nearly nine years of war.

After weeks of steady regime advances in Syria’s northwest, only a two-kilometre section of the M5 remains outside government control, according to the Observatory.

Pro-government forces were closing in Sunday on the last segment southwest of Aleppo, neighbouring Idlib, the Britain-based war monitor said.

“Regime forces have gained new ground and now control several villages near the motorway,” Observatory head Rami Abdul Rahman told AFP.

Fighting was ongoing in the area early Sunday evening with bombing intensifying, he said.

Half a million displaced

Since December, Russian-backed government forces have pressed a blistering assault against Idlib, Syria’s last major opposition bastion, retaking town after town.

The violence has killed more than 300 civilians and sent some 586,000 fleeing towards relative safety nearer the Turkish border.

Some three million people are now trapped in the Idlib region, around half of whom have already fled other parts of the country.

The Syrian army said in a statement Sunday it had recaptured 600 square kilometres (232 square miles) in recent days, comprising “dozens of villages and locations” in south Idlib and west Aleppo provinces.

The Syrian government on Sunday approved a plan aimed at “progressively re-establishing services in liberated areas”, official news agency SANA reported.

That came a day after the army captured the Idlib town of Saraqeb, located on a junction of the M5, state media said.

Troops then pressed north along the motorway past Idlib’s provincial borders and linked up with a unit of Syrian soldiers in Aleppo province, according to the Observatory and state agency SANA.

It was the first time in weeks the two units joined up after waging separate offensives against rebels and jihadists in Idlib and Aleppo.

A little more than half of Idlib province remains in rebel hands, along with slivers of neighbouring Aleppo and Latakia provinces.

Some 50,000 fighters are in the shrinking pocket, many of them jihadists but the majority allied rebels, according to the Observatory.

The United Nations and aid groups have appealed for an end to hostilities in the Idlib region, warning that the exodus risks creating one of the worst humanitarian catastrophes of the nearly nine-year war.