Egyptian police on Tuesday detained former anti-corruption chief Hisham Genena, who had been helping run the election campaign of a challenger to President Abdel-Fattah al-Sisi, his daughter said.
Nada Genena told Reuters by phone that up to 30 policemen had taken Genena from his home in a Cairo suburb in a vehicle.
She witnessed the incident but did not know where he was being taken and gave no further details.
Genena had run the short-lived election campaign of former military chief of staff Sami Anan, who was detained in January and accused by the army of running for office without permission, bringing his presidential bid to a halt.
The National Electoral Commission of Egypt says presidential election will take place between March 26 and March 28.