The Islamic State (IS) terror group abducted 20 people from towns under its control in the northern province of Aleppo, a monitor group reported Monday.

The IS militants arrested the civilians from a number of towns in the northern countryside of Aleppo, where the IS has been engaged in battles against rival rebel groups.

The reason behind the abduction has not been known yet, according to the Syrian Observatory for Human Rights.

A day earlier, the Observatory said the IS militants had killed 37 rival rebels during overnight battles in northern Aleppo.

Another 20 rebels have gone missing during the violent attack IS waged against the town of Um Housh in the northern countryside of Aleppo, the Observatory added.

IS initiated the attack through a suicide car bombing targeting the rebels' town posts, said the Observatory, adding that US-led anti-terror warplanes are believed to have struck IS in that area.

IS lost ten militants in the attack, but gained control of the entire town, a victory deemed crucial for IS militants in their advance to secure positions in the northern countryside of Aleppo.

The UK-based watchdog group said IS aims to advance towards the northern province of Aleppo to sever its northern countryside from the city of Aleppo.

Separately Monday, the Observatory said the Turkish border guards have assaulted a Syrian man who was trying to cross from Aleppo into the Turkish territories.

After beating the man, the Turkish guards threw him in the Syrian side of the borders where he was transported to a hospital, the Observatory said, spelling no further details.

The man is apparently one of the people who are crossing the border to Turkey to later travel to Europe to seek refuge.