(CNN) -- The Egyptian government released on Tuesday one of four Al Jazeera journalists it had detained Sunday night, but continued holding the other three employees of the news network, which is demanding their release.
Correspondent Peter Greste, producer Mohamed Fahmy, producer Baher Mohamed and cameraman Mohamed Fawzy were taken into custody Sunday evening in Cairo, the network said.
Fawzy was released Tuesday morning; the other three men remained in detention and appeared Tuesday before magistrates, Al Jazeera reported.
The Egyptian Interior Ministry said on its Facebook page that security forces arrested a Muslim Brotherhood member and an Australian journalist at a Cairo hotel. Greste, an Australian, previously worked for CNN, Reuters and the BBC.
Fahmy worked for CNN and The New York Times prior to joining the Qatar-based network; Mohamed is a Cairo-based producer for the network.
The ministry said the Muslim Brotherhood member used the hotel to meet with other members and as a media center to broadcast damaging news about the government for Al Jazeera.
"It is outrageous to be treating bona fide journalists in this way," said Al Anstey, managing director of Al Jazeera English, in a statement. "The allegations that are being made are totally false and unfounded. We operate in Egypt legally, the team were working on a number of stories to show our viewers around the world all aspects of the ongoing situation in the country, and every member of our team has huge experience carrying out the highest quality journalism with integrity."
Calling the arrests arbitrary, Al Jazeera said the network "has been subject to harassment by Egyptian security forces," including having its equipment confiscated and offices raided, despite the network not being banned from working in Egypt.
The arrests occurred the day before the Committee to Protect Journalists issued a report saying Egypt, Syria and Iraq have become the deadliest countries for journalists. Seventy journalists were killed in 2013, with six of those deaths in Egypt, the CPJ said.
Egypt's current round of political turmoil began on July 3, when President Mohamed Morsy was ousted in a military coup.
Last week, the military-backed government declared the Muslim Brotherhood a terrorist organization. Police and members of the Muslim Brotherhood have clashed in the streets since then.
CNN's Josh Levs and Ralph Ellis contributed to this report