Islamic State has bolstered its forces north of Syria's second city Aleppo, where it is attacking rivals as part of a broader push beyond its eastern strongholds, a rebel leader and a monitoring group said.
The radical jihadist group has in recent weeks conducted a series of attacks in western areas of Syria including state-held territory and has also staged a major advance into Damascus, where it is battling for control of the Yarmouk refugee camp.
Earlier this week, the group targeted rival rebel factions north of Aleppo with two car bombs, killing at least 31 people, according to the Syrian Observatory for Human Rights, which monitors the conflict.
A rebel commander with fighters in that area said Islamic State had called in reinforcements. "They increased their presence and they are launching an attack," said the rebel who declined to be named, citing the safety of his fighters.
"They are sending messages to terrorise the people, spreading rumours among the people that they are coming back."
The Observatory on Friday reported fighting in a town near the site of the double car bombing.
"Daesh is trying to target the Islamist and (other) fighting factions in the northern Aleppo countryside," said Rami Abdulrahman, who runs the British-based Observatory. Daesh is an Arabic name for Islamic State used by its opponents.
"They are trying to take the initiative."