(REUTERS) - The ISIS (Islamic State in Iraq and Syria) terror group has taken control of a major checkpoint in the Syrian city of Aleppo, amateur footage posted on the Internet appears to show.

The video clip said to be filmed on Sunday (Oct 25) purports to show the chaotic state of what is said to be a Syrian Army checkpoint after it was taken over by ISIS fighters.

Another clip, uploaded to the Internet on Monday (Oct 26), appears to show rebels engaging in heavy fighting with what is said to be Syrian regime forces on the Sheikh Saiid front in Aleppo.

Rebels targeted regime bases in M'amal al-Ismint in southern Aleppo on Sunday, the last clip appears to show, where a series of explosion sends plumes of thick white smoke into the air.

The British-based Syrian Observatory for Human Rights on Saturday (Oct 24) said the main supply route into government-held areas of Aleppo had been cut by fierce fighting between Syrian government forces and ISIS, adding that ISIS fighters launched an attack on a road south-east of the northern city on Friday (Oct 23) morning, initially detonating two car bombs.

The Observatory, which reports on the Syrian war using a network of sources on the ground, said several dozen combatants from both sides had been killed.

ISIS members, speaking to Reuters via Internet from inside Syria, said their group had taken control of the road south-east of Aleppo, Syria's most populous city and commercial hub before the war broke out in 2011.

There was no mention of the battle on Syrian state media, which reported that government forces had seized control of the village of al-Jaboul in a nearby area.

Syrian officials could not be immediately reached for comment.