A statement issued by the Giza security directorate to Aswat Masriya confirmed that Egypt's Homeland Security police had arrested Wednesday the foundation's chairman Hesham Gaafar, without mentioning the reason for his arrest.
Earlier, Kawthar al-Khouli, the director of one of the foundation's projects The Nuun Center for Women and Family Issues, told Aswat Masriya that Mada Foundation for Media Development was raided on Wednesday afternoon.
Gaafar is a journalist and a member of Egypt's Press Syndicate. Among the foundation's main projects is OnIslam.net website which was launched in 2011 and is run by journalists who formerly worked for IslamOnline website which had to shut down its Egypt office the previous year.
Head of the freedoms committee of the Syndicate Khaled El Balshy also confirmed the arrest to Aswat Masriya but had no further details about the reason for his arrest or interrogation.
Khouli said the raid took place while the foundation was running a training programme for mothers. She says the Mada Foundation offers media consultancies and often works on issues related to women and society.
When the masked security personnel stormed the office with their weapons, she explained, there was a state of "panic". She said security forces did not present a warrent.
Eventually, all women including trainees and staff, were let go, except for Gaafar's secretary, Khouli said.
Gaafar was apparently questioned on the premises before being taken away.
Around 15 staff members remain held inside the foundation's office, which is based in the Giza suburb of October 6, she added.
OnIslam.net says it provides "global audience, both Muslims and non-Muslims, with a holistic image of Islam." The website publishes work in both Arabic and English.