Al Jazeera said Egyptian security forces arrested three of its journalists after the interior ministry accused the Qatar-based television channel of broadcasting illegally from a hotel suite together with a member of the Muslim Brotherhood.
Al Jazeera's offices in Cairo have been closed since July 3, when they were raided by security forces hours after the army ousted the Brotherhood's Mohamed Morsi from the presidency.
"State security received information that a member of the [Brotherhood] used two suites in a Cairo hotel to hold meetings with other members of the organization and turned the suites into a press center," the Interior Ministry said.
"[They] made live broadcasts of news that harms homeland security, spreading rumors and false news to Qatar's Al Jazeera channel without permits."
A member of the Brotherhood and an Australian journalist who works for Al Jazeera were arrested and equipment was seized, including broadcast transmitters, the Interior Ministry said in a statement.
Al Jazeera said three journalists from its English news channel had been arrested, a correspondent, a producer and a cameraman.
Qatar was a strong financial backer of the Brotherhood's rule. Its relationship with Cairo has deteriorated in recent months as it vehemently opposes the army's overthrow of Morsi.
Since Morsi's ouster, Egypt has faced some of its worst violence in decades, which the government has blamed on Islamic militants. It declared the Brotherhood a terrorist group last week and has arrested thousands of its members, including Morsi.
US Defense Secretary Chuck Hagel expressed concern about recent developments in Egypt in a call on Sunday to Egyptian army chief General Abdel Fattah al-Sisi, discussing the "balance between security and freedom."
The New York-based Committee to Protect Journalists (CPJ) on Monday classified Egypt alongside Syria and Iraq as one of the most dangerous countries for journalists to operate in.
"Amid stark political polarization and related street violence, things deteriorated dramatically for journalists in Egypt, where six journalists were killed for their work in 2013," the CPJ said.
Egypt is pushing through a political transition that could lead to presidential and parliamentary elections next year.