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.

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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.