By Timour Azhari, Maya Gebeily and Tom Perry DAMASCUS/BEIRUT (Reuters) - Rebel leader Ahmad al-Sharaa's Islamist group is stamping its authority on Syria's state with the same lightning speed that it seized the country,

Syria's brutal civil war rekindled suddenly after 13 years, with rebels staging a shock offensive that forced long-time dictator Bashar al-Assad to flee to Russia.

Tens of thousands of people held in Syria's notorious prisons have been freed in the 10 days since the insurgents began their lightning advance across the country that ended with the toppling of President Bashar Assad.