Syria's regime killed dozens of civilians with air strikes in and around Aleppo city on Friday, June 3, even as it agreed to allow access for ground convoys to deliver aid to 12 besieged areas, AFP reports.

The raids on Aleppo were the most intense in more than a month, with dozens of barrel bombs -- crude, unguided explosive devices -- dropped on rebel-held eastern districts of the city, an AFP correspondent said.

Fourteen people were killed when a bus they were travelling in was hit on the Castello road, a key rebel supply route out of Aleppo, the civil defense said.

At least 43 other civilians were killed in regime strikes on neighbourhoods in the city's rebel-held east, said the civil defense, known as the White Helmets, AFP says.

"There are people under the rubble and we're still looking for the missing," said a volunteer who gave his name as Khaled.

Official news agency SANA said rebel rocket fire killed two children in the regime-controlled west of the city.

The Britain-based Syrian Observatory for Human Rights said the Castello road was now "effectively cut."

"All movement is targeted, be that buses or bystanders," its head Rami Abdel Rahman said, according to AFP.

The observatory later said that regime air strikes killed at least 15 civilians in the Boleel area controlled by Islamic State outside Deir Ezzor city in eastern Syria.

It added that rebel shelling on Friday killed 10 civilians, including a woman and two children in Aleppo’s regime-controlled western districts.