It is six years since the outbreak of the 18-day revolution in Egypt which swept its leader, Hosni Mubarak, from power.

Human rights campaigners say the situation in the country is now far worse than before the uprising, and Mahmoud Hussein, 21, is one of thousands who have been detained in recent years under Egypt's latest strongman, President Abdul Fattah al-Sisi.

He told the BBC's Orla Guerin how his ordeal began.