A car bomb on the outskirts of the Sayeda Zeinab district south of Damascus killed at least six people Monday, a monitoring group said, the third bombing attack in the area this year.

Lebanese group Hezbollah's Al Manar television reported the blast had occurred at a Syrian army checkpoint. It put the death toll at eight.

The Syrian government's chief negotiator at Geneva talks said the blast struck a hospital.

The death toll was expected to rise because of the number of people with serious injuries, the British-based Syrian Observatory for Human Rights said.

Multiple explosions in February killed scores of people in the Sayeda Zeinab area, home to Syria's holiest Shi'ite Muslim shrine, in one of the bloodiest attacks there in Syria's five-year conflict.

A suicide attack there less than a month earlier claimed by ultra-hardline Sunni Muslim group Islamic State group killed 70 people.

Syrian government negotiator Bashar Ja'afari said Monday's blast "that four terrorists carried out" hit a hospital, killing some patients evacuated last week from two rebel-besieged towns in the northwestern province of Idlib. He said 10 people were killed.