The grand Umayyad mosque in Aleppo is about 1400 years old. (Khaled al-Hariri/Reuters)

Syrian activists say rebels are clashing with government forces around a historic 12th century mosque inside the walled old city of Aleppo.

The Britain-based Syrian Observatory for Human Rights says the clashes Thursday are concentrated around the Umayyad Mosque with rebels controlling part of it and government troops holding another part.

The Observatory, which relies on reports from activists on the ground, also says rebels continue to battle troops for control of a police academy west of Aleppo.

Aleppo, Syria's commercial capital, has been a key battleground in the civil war since rebels entered in July.