International peace envoy Lakhdar Brahimi is to head to Damascus on Thursday to meet Syria’s President Bashar al-Assad, an Arab diplomat in Cairo says, as fresh bloodshed grips the north of the country.

In a single incident, rebels killed at least 18 soldiers in a car bomb and ground attack on a military position in Idlib province of northwest Syria, the Syrian Observatory for Human Rights said.

Separately, four Syrian Armenians were killed and 13 wounded in the war-battered commercial capital Aleppo on the way home from the airport after a trip to Yerevan.

Speaking of the assault in Idlib, Observatory head Rami Abdel Rahman said “there were 70 to 100 soldiers there when the attack occurred” in the town of Saraqeb.

“Twenty soldiers escaped, and clashes are still going on,” he added, saying details of the incident were still sketchy and that he could not say whether the car bombing was a suicide attack.

He also said rebels had encircled two other army positions near Saraqeb and fired rockets on checkpoints elsewhere in the province.

Meanwhile, a friend of the Syrian Armenians who died in Aleppo told AFP: “It’s not obvious who opened fire, but the result is that five cars were attacked and four Armenians were killed and 13 or 14 others were wounded.”

Outside Aleppo, fighting erupted at dawn in the Nayrab area, around five kilometres from the airport, which remained fully operational, the Observatory said.

Over the past several weeks, rebels have taken to attacking military airfields in an attempt to prevent them from being used for launching air strikes, while commercial facilities have been left unscathed.

Meanwhile, the army shelled a string of neighbourhoods in central Aleppo, including Suleiman al-Halabi, Sheikh Khodr and Qadi Askar, the Britain-based Observatory said.

Helicopter gunships also strafed the rebel district of Bustan al-Basha, a witness said, and the Observatory reported that rebels used rocket-propelled grenades to attack a security branch in the adjacent Midan neighbourhood.

Elsewhere, a boy and a girl were killed and dozens of civilians wounded when the army shelled the rebel village of Latamneh in the central province of Hama, said the Observatory, which gathers its information from a wide network of activists.

Also in Hama, the Observatory reported on Wednesday afternoon that 20 bodies, including those of two children, had been found in farmlands in Halfaya village over the previous 24 hours, following an assault by government forces.

In eastern Syria, troops shelled several districts of Deir Ezzor city, and an unspecified number of people were killed in air strikes on the town of Albu Kamal on the border with Iraq, the Observatory said.

Overall, at least 44 people – 22 soldiers, 17 civilians and five rebels – died in Syria on Wednesday, the Observatory said.

More than 27,000 people have been killed since the revolt against President Bashar al-Assad broke out in March 2011, according to Observatory figures.

In Cairo, an Arab League diplomat said UN-Arab League envoy Brahimi would head for Damascus on Thursday and meet with Assad the following day, but gave no further details.

Coupled with the violence is the humanitarian crisis caused by the large number of people fleeing the country or displaced within its borders.

The UN refugee agency said the number of civilians who have fled nearly 18 months of violence has reached more than 250,000. And it says more than 1.2 million civilians, more than half of them children, have been displaced inside Syria.

In Beirut, film star and UN special envoy Angelina Jolie said on Wednesday she was moved at how Lebanese families were opening their homes to Syria refugees, after Beirut ruled out setting up camps for them.

“I was very moved today to meet again with the Syrian families. And to meet them here, not in a camp, but in homes where they are welcomed and protected,” the Oscar-winning star told reporters.

The Lebanese government has ruled out the possibility of establishing refugee camps amid fears that the crisis in neighbouring Syria could spill across its borders.

Already, areas of northern Lebanon where a large number of refugees have concentrated have come under shelling from inside Syria.