Global rights groups have strongly condemned Egypt's decision to try journalists working for Qatari-owned Al-Jazeera television, which Cairo accuses of backing the Muslim Brotherhood ousted from power by the military in July.
Doha-based Al-Jazeera, which has angered the new authorities for its coverage of a deadly crackdown on the Brotherhood and supporters of ousted Islamist president Mohamed Morsi, says the charges are "silly and not based on any reality".
Prosecutors say they have referred to trial 20 of the network's journalists, accusing them of portraying Egypt as being in a state of "civil war" and "airing false news".
They include 16 Egyptians, two of whom have been in jail since the summer, and four foreigners -- Australian Peter Greste, two Britons and a Dutch woman.
If convicted, the foreigners could face up to seven years in jail and the Egyptians 15.
Officials also say the defendants were operating without official accreditation.
Amnesty International secretary general Salil Shetty said the decision to prosecute "sends the chilling message that only one narrative is acceptable in Egypt today -- that which is sanctioned by the Egyptian authorities".
"Journalists cannot operate freely in a climate of fear. The latest development is a brazen attempt to stifle independent reporting in Egypt."
Greste himself, in a letter written from Tora prison where he is being held and published Thursday by Al-Jazeera, described what he sees as a lack of press freedom in Egypt.
"The state will not tolerate hearing from the Muslim Brotherhood or any other critical voices," he wrote. "The prisons are overflowing with anyone who opposes or challenges the government."
But Egyptian officials insist the channel has been working for the benefit of Doha, a strong supporter of the Muslim Brotherhood that has even hosted some of its members who have fled the crackdown.
"It is a Qatari network and Qatar is the only Gulf Arab country supporting the Muslim Brotherhood," a high-ranking official told AFP on condition of anonymity.
"What Jazeera is doing is not journalism, but it is pro-Brotherhood activism."
In the past, Al-Jazeera, especially its Arabic-language service, has come under criticism for allegedly biased reporting in the Arab world.
And Andrew Hammond, Middle East analyst with the European Council on Foreign Relations, says the channel's editorial policy follows Doha's line.
The "Arabic channel, not the English one, does reflect the position of the Qatari government", he said. "In Arabic they are pushing for pro-Islamist policies or parties.
"For instance, under Morsi the channel's debates and programmes did not question policies of the Muslim Brotherhood, while it was a big issue in the country."
Doha has backed Islamists in several countries swept by the Arab Spring uprisings since 2011, often sparking a backlash from the Islamists' opponents, who accuse gas-rich Qatar of using its wealth to further that agenda.
Relations between Egypt and Qatar have been strained since Morsi's ouster, particularly after Doha criticised Cairo's blacklisting of the Muslim Brotherhood as a "terrorist organisation".
Global media watchdog Reporters Without Borders said that since Morsi's fall, the authorities have "hounded journalists suspected of direct or indirect links with the Muslim Brotherhood".
On July 3, the day Morsi was deposed, the authorities closed Misr 25 television, operated by the Freedom and Justice Party, the Brotherhood's political arm. It also shut three other TV stations supporting Morsi -- Al-Hafiz, Al-Nas and Rahma.
Two months later, Al-Jazeera Mubasher Misr, the Cairo-based affiliate of Al-Jazeera, was declared illegal and forbidden to operate.
And since Morsi's ouster, foreign journalists have often faced mobs of angry Brotherhood opponents.
Last Friday, a Cairo mob set upon two German reporters working for Germany's ARD and their driver as they covered a bomb attack, branding them "traitors" and "lackeys of the Muslim Brotherhood", the public broadcaster said.
Reporters Without Borders said it was simply "stunned and appalled" by the move to try the Al-Jazeera journalists.
"It is just deepening the divisions in Egypt's increasingly polarised society and is bringing further discredit on the Egyptian authorities in the eyes of the international public opinion," it said.
Washington has also criticised Cairo.
"The government's targeting of journalists and others on spurious claims is wrong and demonstrates an egregious disregard for the protection of basic rights and freedoms," said US State Department spokeswoman Jen Psaki.
But Egyptian foreign ministry spokesman Badr Abdelatty dismissed that criticism.
It is "unacceptable that a state or a foreign party interferes in the affairs of the Egyptian judiciary", which is "transparent and independent", he said.