An Egyptian journalist was arrested early on Saturday from his home in the Nile Delta city of Behiera, his brother said.
Mahmoud Qaoud said police took his brother Ahmed, who works for the daily El-Dostour, and confiscated three laptops and three mobile phones.
Head of the freedoms committee at the press syndicate Khaled El-Belshy confirmed receiving a complaint from the journalist’s brother and said he would look into the needed procedures.
Ahmed is accused of participating in an illegal protest on Friday and joining the banned Muslim Brotherhood.
Security forces have been rounding up thousands of Brotherhood members and supporters since president Mohamed Morsi's ouster in 2013.
Charges against Brotherhood loyalists have ranged from participating in unauthorised protests to terrorism-related crimes.
On world press freedom day, Amnesty International said at least 18 journalists and media workers remain in detention in Egypt.
At least six journalists have been killed while covering protests since June 2013, Amnesty said.
Cases detailed in Amnesty's report include freelance photojournalist Mahmoud Abu Zied, known as “Shawkan,” who was arrested while covering the dispersal of the pro-Morsi Rabaa El-Adawiya sit-in in summer 2013, and has been in detention since then.
The London-based rights group said that the “pattern of arrests, charges and prosecution of journalists suggests that they are aimed at silencing the government’s political opponents and critics.”
“Amnesty International is warning that today there is no safe space for a journalist or blogger in Egypt to criticize the authorities’ political or human rights records, or to peacefully express their opposition,” the group said, calling for the immediate and unconditional release of detained reporters.
The interior ministry has regularly denied arresting people for their political views and says the arrested journalists face criminal charges.
The newly elected press syndicate head Yehia Qallash has repeatedly promised to tackle the problem of arrested journalists.