Monday's blast, carried out by a extremist group affiliated with al-Qaeda, hit near a military complex in the town of al-Douwairinah near Aleppo's international airport, Mohammad al-Hadi, an activist in the city, said.

"The car was filled with six tones of explosives," he told Al Jazeera.

The blast was one of the largest attacks targeting Syrian soldiers who have been struggling with a massive insurgency to save their country.

Activists posted a video on social media that purports to show the moment of the explosion. However, the authenticity of the video could not be verified. 

The terrorist attack came hours after another car bomb attack targeted a checkpoint near a military airport in Damascus, the Syrian capital.

There were conflicting reports about the number of casualties but some sources say at least 20 soldiers were killed in the attack.

Report of the terrorist attack comes amid grave concerns about dimensions of the terrorist war in Syria getting wider, fallowing United States decisions to arm militants in Syria to gain more power against the national army of the country.

The move which is against international regulations has been strongly rejected by Russia and Syria.

On Monday Russian president Vladimir Putin said, "I think you will not deny that one does not really need to support the people who not only kill their enemies, but open up their bodies, eat their intestines, in front of the public and cameras," referring to a video footage on the Internet of a rebel fighter eating the heart of a government soldier.