An influential Sudanese imam had to be removed from a mosque in the capital, Khartoum, after worshippers confronted him for not leading protests against embattled President Omar al-Bashir.
In a video shared on social media, a man appears to shout at imam Abdul Hai Yusuf, who often backs the government: "Get up and lead us from this mosque!"
A frantic crowd then chants "downfall [of the regime] only".
Police fired tear gas at protesters who marched after Friday prayers.
Three weeks of demonstrations have left 22 people dead across the country.The protests, initially against the rising cost of fuel and bread, have morphed to calls for Mr Bashir to step down to end his 30-year rule.
What happened on Friday?
A video shared on Facebook appears to show a member of the Khatim al-Mursaleen mosque challenging Mr Yusuf, a Saudi-educated imam./BBC