Egyptian police arrested an Australian journalist, an American student and their Egyptian translator on suspicion of paying Egyptians to stage protests against the authorities, a security official said.
Freelance reporter Austin Mackell, American student Derek Ludovici and translator Aliya Alwi were detained in the Nile Delta city of Mahalla on the same day activists held student strikes to mark the first anniversary of president Hosni Mubarak's overthrow.
General Mostafa Baz, police chief of the northern Gharbiya province, told reporters the three were suspected of having coordinated over the Internet to meet in Mahalla, which has a history of labour strikes, to "incite people to protest."
A security official said people in Mahalla had complained to police that all three were paying people to protest. The authorities have in the past blamed foreigners for plotting unrest.
Alwi said on her Twitter account that they were being charged with inciting protests and vandalism.
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"Witnesses have been produced to confirm it," she wrote. "Report against us, filed now. Many witnesses saw us 'offering money to youth to vandalise and cause chaos.'"
She later tweeted that they were being handed over to intelligence services.
Veteran Egyptian labour activist Kamal al-Fayyumi was also arrested, Baz said, although it was not immediately clear why he had been detained.
Australia's foreign office confirmed Mackell's arrest and said diplomatic officials in Cairo were "seeking advice from Egyptian police on possible charges."
"(Mackell) has confirmed he is being treated appropriately by local police authorities. He confirmed his intention to engage a legal representative," a foreign office spokeswoman said.
The authorities, including the ruling military which took charge after Mubarak's ouster, have accused foreigners of stirring unrest in Egypt which has seen a spate of deadly protests over past months.
In June, security forces arrested a US-Israeli citizen they accused of spying and inciting Egyptians to protest. The man was released in October in a prisoners exchange deal.