Syria army preparing for battles in Aleppo

Islamic State militants battled rival insurgent groups on Wednesday north of the city of Aleppo, where officials say the Syrian army is preparing an offensive of its own backed by Iranian soldiers and Russian jets, Reuters reported.

A rebel fighter and a group monitoring the war said Islamic State fighters took control of parts of the towns of Ahras and Tel Jabin, about 12 km (8 miles) north of Aleppo, before being pushed back.

Gains by Islamic State north of Aleppo would threaten the supply lines of rival rebels inside the city, which is divided between insurgents and government forces. The Syrian Observatory for Human Rights said the road used by Aleppo residents heading north to the Turkish border remained closed on Wednesday.

"Today there are fierce battles between us and Daesh in Ahras, Tel Jabin, and rural northern Aleppo," said Hassan Haj Ali, head of the Liwa Suqour al-Jabal rebel group, using another name for Islamic State.

His unit is one of several foreign-backed insurgent forces which find themselves fighting Islamic State on the ground, at the same time as they are bombed by Russian jets and are bracing for further ground attacks by the army and its foreign allies.

"There are mobilizations by the regime in most parts of Aleppo, particularly in Bashkoy," he said, referring to another town north of Aleppo, which before Syria's civil war began in 2011 was the country's biggest city and a major commercial and industrial center.

"There were advances (by Islamic State) at dawn but we were able to recover Ahras entirely. There are battles in Tel Jabin," said Ali, speaking to Reuters via an internet messaging system.

The Observatory reported fighting between Islamic State fighters and government forces trying to advance towards an air base besieged by the jihadist group in Aleppo province.

Any further escalation in the Aleppo area near the Turkish border will likely further anger NATO member Ankara which opposes President Bashar al-Assad, backs the insurgents, and has expressed deep concern at Russian air strikes.