Three journalists working for the Al-Jazeera broadcaster in Cairo have been arrested by Egyptian police.
The Interior Ministry said the journalists had held illegal meetings with the banned Muslim Brotherhood.
The Muslim Brotherhood was declared a terrorist organization last week.
The military-backed interim government launched a crackdown on the movement following President Mohamed Morsi’s removal from power.
Thousands of Muslim Brotherhood members, including its leadership, have been arrested and many put on trial.
The journalists, who work for Al-Jazeera English, are understood to have been detained late on Sunday night.
They are Mohamed Fadel Fahmy, who holds Canadian nationality, Peter Greste, an Australian, and an unnamed cameraman who is said to have been arrested at home.
The Egyptian Interior Ministry said in a statement that cameras, recordings and other material had been seized from rooms at a hotel in Cairo.
It accused the journalists of broadcasting news that were “damaging to national security”.
Observers say Egypt’s media environment has been highly charged since Mohamed Morsi’s overthrow.
Several Islamist channels were closed down immediately after the military intervention in the summer. Journalists working for them were temporarily detained.
The latest arrests come after fresh deadly clashes between police and Muslim Brotherhood supporters across Egypt.
Three people were killed – in Cairo, southern Minya province and the Nile Delta – during the violence.
Security forces detained some 265 Muslim Brotherhood supporters, officials said.
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