Egypt detains leading youth activist Ahmed Maher
Middle EastEgyptian security forces have detained a prominent activist on suspicion of inciting an anti-government protest.
Ahmed Maher, who leads the April 6 Youth Movement, was arrested at Cairo airport after flying back from the US, officials said.
The April 6 Youth Movement was at the forefront of protests that overthrew former leader Hosni Mubarak in 2011.
Mr Mubarak's retrial on charges linked to the revolt is due to begin on Saturday.
He is charged alongside a former interior minister and six former security chiefs with complicity in the killing of hundreds of protesters.
Mr Mubarak will also face charges of financial corruption alongside his two sons, Alaa and Gamal.
The official Mena news agency said Mr Maher's passport was confiscated and he was ordered to be detained for four days.
A security official quoted by AP news agency said Mr Maher was accused of "incitement" following a demonstration in March against the country's interior minister.
Protesters hurled underwear at the minister's house following a police crackdown on the activist group.
Mr Maher is being held on the premises of the prosecutor's office in Cairo's eastern district of Nasr City, the official said.