Security forces in Egypt have used tear gas to disperse demonstrators in Cairo, after hundreds of people gathered demanding the resignation of President Abdul Fattah Sisi.

The protests were some of the first since he took power in 2014, and came after a video alleging government corruption was posted online by businessman and actor Mohamed Ali.

President Sisi has dismissed the allegations as "lies and slander".

The BBC's Sally Nabil reports from Tahrir Square in the city centre.